2001 LAS VEGAS, NEVADA (LAS)

Las Vegas is situated near the center of a broad desert valley, which is almost surrounded by mountains ranging from 2,000 to l0,000 feet higher than the floor of the valley. This Vegas Valley, comprising about 600 square miles, runs from northwest to southeast, and slopes gradually upward on each side toward the surrounding mountains. Weather observations are taken at McCarran Airport, 7 miles south of downtown Las Vegas, and about 5 miles southwest and 300 feet higher than the lower portions of the valley. Since mountains encircle the valley, drainage winds are usually downslope toward the center, or lowest portion of the valley. This condition also affects minimum temperatures, which in lower portions of the valley can be from 15 to 25 degrees colder than recorded at the airport on clear, calm nights.

The four seasons are well defined. Summers display desert conditions, with maximum temperatures usually in the 100 degree range. The proximity of the mountains contributes to the relatively cool summer nights, with the majority of minimum temperatures in the mid 70s. During about 2 weeks almost every summer warm, moist air predominates in this area, and causes scattered thunderstorms, occasionally quite severe, together with higher than average humidity. Soil erosion, especially near the mountains and foothills surrounding the valley, is evidence of the intensity of some of the thunderstorm activity. Winters, on the whole, are mild and pleasant. Daytime temperatures average near 60 degrees with mostly clear skies. The spring and fall seasons are generally considered most ideal, although rather sharp temperature changes can occur during these months. There are very few days during the spring and fall months when outdoor activities are affected in any degree by the weather.

The Sierra Nevada Mountains of California and the Spring Mountains immediately west of the Vegas Valley, the latter rising to elevations over 10,000 feet above the valley floor, act as effective barriers to moisture moving eastward from the Pacific Ocean. It is mainly these barriers that result in a minimum of dark overcast and rainy days. Rainy days average less than one in June to three per month in the winter months. Snow rarely falls in this valley and it usually melts as it falls, or shortly thereafter. Notable exceptions have occurred.

Strong winds, associated with major storms, usually reach this valley from the southwest or through the pass from the northwest. Winds over 50 mph are infrequent but, when they do occur, are probably the most provoking of the elements experienced in the Vegas Valley, because of the blowing dust and sand associated with them.

Based on the 1951–1980 period, the average first occurrence of 32 degrees Fahrenheit in the fall is November 21 and the average last occurrence in the spring is March 7.

NORMALS, MEANS, AND EXTREMES

LAS VEGAS, NV (LAS)

LATITUDE:    LONGITUDE:     ELEVATION (FT):    TIME ZONE:    WBAN: 23169

36 04′ 44″ N  115 09′ 19″ W  GRND: 2127  BARO: 2091  PACIFIC (UTC + 8)

	ELEMENT	POR	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	YEAR
TEMPERATURE F	NORMAL DAILY MAXIMUM	30	57.3	63.3	68.8	77.5	87.8	100.3	105.9	103.2	94.7	82.1	67.4	57.5	80.5
	MEAN DAILY MAXIMUM	53	56.4	62.4	69.2	78.1	87.7	98.4	104.0	102.0	94.3	81.2	66.2	57.1	79.7
	HIGHEST DAILY MAXIMUM	53	77	87	91	99	109	115	116	116	113	103	87	77	116
	YEAR OF OCCURRENCE		1975	1986	1966	2000	1951	1994	1998	1979	1950	1978	1988	1980	JUL 1998
	MEAN OF EXTREME MAXS.	53	67.9	74.5	82.7	92.2	100.9	110.0	112.2	110.0	104.8	94.3	79.2	68.1	91.4
	NORMAL DAILY MINIMUM	30	33.6	38.8	43.8	50.7	60.2	69.4	76.2	74.2	66.2	54.3	42.6	33.9	53.7
	MEAN DAILY MINIMUM	53	34.3	38.9	44.1	51.5	60.7	69.9	76.4	74.9	66.6	54.3	42.0	34.5	54.0
	LOWEST DAILY MINIMUM	53	8	16	23	31	40	48	60	56	46	26	21	11	8
	YEAR OF OCCURRENCE		1963	1989	1971	1975	1964	1993	1987	1968	1965	1971	1952	1990	JAN 1963
	MEAN OF EXTREME MINS.	53	23.3	27.5	32.5	39.6	47.6	56.7	66.7	65.9	55.4	42.2	30.1	24.2	42.6
	NORMAL DRY BULB	30	45.5	51.1	56.3	64.1	74.0	84.9	91.1	88.7	80.5	68.3	55.0	45.7	67.1
	MEAN DRY BULB	53	45.4	50.7	56.6	64.6	74.2	84.1	90.3	88.5	80.4	67.9	54.1	45.7	66.9
	MEAN WET BULB	18	38.2	41.5	45.5	48.9	54.3	58.8	63.8	60.6	58.6	48.0	42.4	34.7	49.6
	MEAN DEW POINT	18	25.2	27.3	28.3	27.7	32.3	35.0	43.6	43.0	39.3	29.8	26.6	21.1	31.6
	NORMAL NO. DAYS WITH:
	MAXIMUM 90	30	0.0	0.0	*	3.3	15.3	25.8	30.5	29.9	21.8	5.6	0.0	0.0	132.2
	MAXIMUM 32	30	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	*	0.1
	MINIMUM 32	30	13.0	4.7	1.3	0.1	0.0	0.0	0.0	0.0	0.0	0.1	2.2	11.4	32.8
	MINIMUM 0	30	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
H/C	NORMAL HEATING DEG. DAYS	30	605	389	292	143	14	0	0	0	0	62	304	598	2407
	NORMAL COOLING DEG. DAYS	30	0	0	22	116	293	597	809	735	465	164	0	0	3201
RH	NORMAL (PERCENT)	30	45	40	33	25	21	16	21	26	25	29	37	45	30
	HOUR 04 LST	30	55	50	44	35	31	24	29	35	34	38	46	54	40
	HOUR 10 LST	30	41	36	29	22	19	15	19	24	22	25	33	40	27
	HOUR 16 LST	30	30	26	21	16	13	10	15	17	17	19	26	32	20
	HOUR 22 LST	30	49	42	35	26	22	17	22	26	26	31	40	49	32
S	PERCENT POSSIBLE SUNSHINE	47	77	81	83	87	88	93	88	88	91	87	81	78	85
W/O	MEAN NO. DAYS WITH:
	HEAVY FOG(VISBY 1/4 MI)	54	0.3	0.1	0.1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.1	0.7
	THUNDERSTORMS	54	0.0	0.2	0.4	0.5	1.0	1.0	3.8	3.8	1.5	0.5	0.2	0.0	12.9
CLOUDINESS	MEAN:
	SUNRISE-SUNSET (OKTAS)			1	1.6		0.8	0.0
	MIDNIGHT-MIDNIGHT (OKTAS)	1					0.8
	MEAN NO. DAYS WITH:
	CLEAR	1	4.0	1.0	9.0		27.0	16.0
	PARTLY CLOUDY	1	2.0	3.0	6.0		1.0
	CLOUDY	1	1.0	3.0			1.0	1.0
PR	MEAN STATION PRESSURE(IN)	29	27.80	27.79	27.70	27.60	27.60	27.60	27.60	27.60	27.60	27.70	27.80	27.81	27.68
	MEAN SEA LEVEL PRES. (IN)	18	30.13	30.04	29.94	29.87	29.79	29.97	29.80	29.83	29.85	29.95	30.06	30.15	29.95
WINDS	MEAN SPEED (MPH)	37	7.4	8.6	10.3	11.0	11.4	11.4	10.4	9.8	9.0	8.1	7.7	7.0	9.3
	PREVAIL. DIR (TENS OF DEGS)	22	25	25	24	22	22	20	18	18	24	24	24	25	24
	MAXIMUM 2-MINUTE:
	SPEED (MPH)	6	45	46	46	44	56	47	45	43	41	46	40	48	56
	DIR. (TENS OF DEGS)		23	22	33	21	22	33	03	32	16	33	24	34	22
	YEAR OF OCCURRENCE		1996	2001	2001	1999	2000	1998	1998	1998	1998	1996	2001	2000	MAY 2000
	MAXIMUM 5-SECOND:
	SPEED (MPH)	6	52	54	56	51	64	54	54	61	49	52	49	56	64
	DIR. (TENS OF DEGS)		24	20	34	34	26	33	04	16	23	33	24	33	26
	YEAR OF OCCURRENCE		1999	2001	2000	1997	2000	1998	1998	1998	1998	1996	2001	1999	MAY 2000
PRECIPITATION	NORMAL (IN)	30	0.48	0.48	0.42	0.21	0.28	0.12	0.35	0.49	0.28	0.21	0.43	0.38	4.13
	MAXIMUM MONTHLY (IN)	53	3.00	2.89	4.80	2.44	0.96	0.97	2.48	2.59	2.06	1.22	2.22	1.71	4.80
	YEAR OF OCCURRENCE		1995	1998	1992	1965	1969	1990	1984	1957	1997	1992	1965	1992	MAR 1992
	MINIMUM MONTHLY (IN)	53	T	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	YEAR OF OCCURRENCE		1984	1977	1972	1962	1970	1982	1981	1980	1971	1979	1980	1981	JUN 1982
	MAXIMUM IN 24 HOURS (IN)	53	1.09	1.30	1.27	0.97	0.83	0.97	1.36	2.59	1.07	1.09	1.78	0.95	2.59
	YEAR OF OCCURRENCE		1990	1993	1992	1965	1987	1990	1984	1957	1963	1992	1960	1977	AUG 1957
	NORMAL NO. DAYS WITH:
	PRECIPITATION 0.01	30	2.9	2.8	3.3	1.9	1.5	0.8	2.4	3.1	1.9	1.8	2.1	2.6	27.1
	PRECIPITATION 1.00	30	0.0	*	0.0	0.0	0.0	0.0	0.1	0.1	*	0.0	0.1	0.0	0.3
SNOWFALL	NORMAL (IN)	30	0.8	0.1	0.*	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.1	1.1
	MAXIMUM MONTHLY (IN)	48	16.7	1.4	0.1	T	0.0	0.0	0.0	T	0.0	T	4.0	2.0	16.7
	YEAR OF OCCURRENCE		1949	1990	1976	1970				1989		1956	1964	1967	JAN 1949
	MAXIMUM IN 24 HOURS (IN)	48	9.0	6.9	0.1	T	0.0	0.0	0.0	T	0.0	T	4.0	2.0	9.0
	YEAR OF OCCURRENCE		1974	1979	1976	1970				1989		1956	1964	1967	JAN 1974
	MAXIMUM SNOW DEPTH (IN)	47	8	6	0	0	0	0	0	0	0	0	3	2	8
	YEAR OF OCCURRENCE		1974	1979									1964	1967	JAN 1974
	NORMAL NO. DAYS WITH:
	SNOWFALL 1.0	30	0.2	0.*	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.1	0.*	0.3

PRECIPITATION (inches) 2001 LAS VEGAS, NV (LAS)
YEAR	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANNUAL
1972	0.00	T	0.00	0.07	0.46	0.32	0.13	0.84	0.63	1.12	1.09	0.19	4.85
1973	0.49	1.64	1.83	0.35	0.09	0.03	T	0.08	T	0.02	0.14	0.01	4.68
1974	2.00	0.11	0.16	T	T	0.00	0.58	0.08	0.16	0.61	0.23	0.59	4.52
1975	0.01	0.05	1.07	0.42	0.35	T	0.26	0.06	1.17	0.03	T	0.05	3.47
1976	0.00	2.49	0.02	0.13	0.34	0.00	1.95	0.00	1.09	0.70	0.02	0.03	6.77
1977	0.21	0.00	0.28	0.01	0.72	0.05	T	1.38	0.19	0.06	0.01	1.06	3.97
1978	1.00	1.51	1.13	0.36	0.54	0.00	0.19	0.53	0.03	0.62	0.59	1.15	7.65
1979	2.18	0.07	0.96	0.06	0.35	0.00	0.78	2.12	T	0.00	0.03	0.24	6.79
1980	1.45	2.25	0.94	0.18	0.15	T	0.43	0.00	0.18	0.04	0.00	0.01	5.63
1981	0.09	0.20	1.44	0.02	0.50	T	0.00	0.20	0.25	0.15	0.29	0.00	3.14
1982	0.09	1.10	0.29	0.01	0.31	0.00	0.05	0.71	0.07	0.04	0.60	0.72	3.99
1983	0.43	0.32	0.90	0.45	0.16	T	0.06	1.25	0.50	0.26	0.10	0.43	4.86
1984	T	0.03	T	0.04	0.00	0.22	2.48	0.99	0.47	T	0.94	1.68	6.85
1985	0.19	0.02	0.06	0.31	T	0.02	0.13	0.00	0.08	0.07	0.37	0.02	1.27
1986	0.23	0.15	0.32	0.10	0.28	T	0.13	0.04	0.05	0.07	0.81	0.47	2.65
1987	1.13	0.45	0.49	0.17	0.90	0.13	0.13	0.01	T	0.49	1.80	0.89	6.59
1988	0.65	0.26	0.00	0.76	T	0.04	0.04	0.46	T	0.00	T	0.08	2.29
1989	0.51	0.06	0.05	T	0.64	T	0.05	0.80	T	T	0.00	T	2.11
1990	1.18	0.37	T	0.18	T	0.97	0.59	T	0.19	0.17	0.10	T	3.75
1991	0.21	0.54	1.01	T	0.05	0.19	0.54	0.78	0.06	0.06	0.38	0.24	4.06
1992	0.45	1.30	4.80	0.02	0.05	0.09	0.03	0.21	0.00	1.22	0.00	1.71	9.88
1993	1.63	2.52	0.14	0.01	0.01	0.08	0.00	0.26	0.00	0.02	0.17	0.21	5.05
1994	0.04	0.48	0.13	T	0.01	0.00	0.11	0.08	0.35	T	0.28	1.08	2.56
1995	3.00	0.03	0.39	0.03	0.16	0.02	T	0.05	T	T	0.00	0.01	3.69
1996	0.13	0.14	0.10	0.00	0.13	T	1.18	T	0.00	0.11	0.79	0.18	2.76
1997	0.30	T	0.00	0.04	T	T	0.60	0.33	2.06	T	0.23	0.07	3.63
1998	0.17	2.89	1.03	0.14	0.13	0.03	0.46	0.23	1.29	0.22	0.33	0.43	7.35
1999	T	0.08	T	0.73	T	0.14	2.18	0.25	0.35	T	0.00	T	3.73
2000	T	1.59	0.21	T	T	T	T	0.71	0.00	0.92	T	0.04	3.47
2001	0.87	2.21	0.16	0.04	0.02	T	0.39	0.05	T	0.00	0.09	0.11	3.94
POR= 65 YRS	0.54	0.54	0.49	0.22	0.18	0.08	0.44	0.40	0.35	0.22	0.31	0.38	4.15

AVERAGE TEMPERATURE (F) 2001 LAS VEGAS, NV (LAS)
YEAR	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANNUAL
1972	42.3	52.0	63.7	65.1	74.5	84.7	93.1	86.5	78.0	63.5	49.7	41.3	66.2
1973	40.9	49.6	50.7	62.2	76.7	85.2	91.7	87.6	78.9	67.7	53.4	46.2	65.9
1974	41.0	48.9	59.5	63.4	77.0	89.1	88.8	87.7	83.4	69.3	54.8	44.4	67.3
1975	45.3	48.8	53.9	56.6	72.5	83.8	90.3	87.5	81.7	66.1	53.0	48.2	65.6
1976	46.9	53.2	53.4	62.6	77.8	81.5	86.9	85.5	78.7	66.5	58.0	46.4	66.5
1977	45.7	54.2	52.6	68.6	67.7	88.0	92.4	90.1	80.6	71.4	57.2	51.9	68.4
1978	47.9	52.1	59.9	63.1	73.1	87.1	91.9	89.0	79.0	73.5	54.2	42.9	67.8
1979	41.1	48.4	56.0	66.1	75.4	85.5	91.1	85.9	85.3	70.7	51.6	47.2	67.0
1980	49.5	53.2	54.2	63.5	69.0	83.9	92.0	90.2	81.4	68.9	56.8	52.7	67.9
1981	51.1	52.5	56.4	70.6	74.3	88.8	92.7	90.0	82.5	64.4	58.0	48.8	69.2
1982	45.6	50.5	55.1	63.8	73.6	81.5	88.1	87.3	77.9	63.0	50.5	44.5	65.1
1983	46.6	51.7	56.4	58.5	72.8	82.8	88.5	83.8	82.5	67.8	55.3	47.9	66.2
1984	47.1	50.1	57.9	63.1	80.7	83.5	88.2	85.4	81.7	63.0	52.7	44.0	66.5
1985	44.4	47.4	54.9	68.2	76.9	87.4	92.0	89.9	75.4	67.3	51.7	48.3	67.0
1986	51.7	55.8	63.0	66.2	76.6	87.8	87.6	91.2	75.4	65.0	55.8	46.0	68.5
1987	44.7	51.4	54.6	68.4	74.5	86.3	86.9	88.2	81.2	71.0	53.4	42.5	66.9
1988	45.1	52.4	58.1	64.2	73.4	85.3	92.6	86.9	79.1	74.9	56.0	46.0	67.8
1989	43.9	50.0	63.4	72.7	75.7	85.3	93.4	86.9	80.0	67.2	57.3	48.0	68.7
1990	45.2	48.8	60.5	68.8	74.5	85.9	90.8	87.8	82.0	69.2	55.1	40.2	67.4
1991	45.5	55.9	52.7	64.2	69.9	82.1	90.2	87.8	81.9	72.2	55.2	47.0	67.1
1992	45.9	54.1	56.8	70.5	77.7	83.2	88.7	90.5	83.7	70.9	52.7	43.6	68.2
1993	45.7	50.1	60.9	67.5	77.0	82.5	89.4	88.5	81.3	69.1	51.5	46.3	67.5
1994	49.3	48.5	62.7	67.6	76.6	90.3	93.3	92.9	83.1	67.2	49.4	47.5	69.0
1995	47.5	58.7	57.9	64.8	71.0	80.9	92.4	93.1	83.7	69.4	59.8	48.9	69.0
1996	48.5	54.8	59.8	68.3	77.3	87.0	93.2	91.9	80.4	66.8	56.5	47.9	69.4
1997	48.3	51.7	62.7	65.4	81.6	84.3	88.2	90.7	81.3	67.3	56.2	45.9	68.6
1998	48.7	49.4	56.6	61.1	70.0	80.0	91.7	92.0	80.0	66.6	54.8	47.8	66.6
1999	50.5	52.7	60.6	60.9	75.3	85.2	88.2	88.0	81.6	71.6	58.8	48.7	68.5
2000	51.4	53.6	58.6	71.2	80.8	88.7	92.3	90.5	81.7	67.3	50.2	49.5	69.7
2001	46.4	49.8	60.6	65.0	82.2	87.9	90.3	91.9	85.1	72.1	58.6	45.4	69.6
POR= 65 YRS	45.2	50.1	56.3	64.5	74.1	83.6	89.9	88.2	80.1	67.6	53.7	45.9	66.6

REFERENCE NOTES:

PAGE 1:

THE TEMPERATURE GRAPH SHOWS NORMAL MAXIMUM AND NORMAL MINIMUM DAILY TEMPERATURES (SOLID CURVES) AND THE ACTUAL DAILY HIGH AND LOW TEMPERATURES (VERTICAL BARS).

PAGE 2 AND 3:

H/C INDICATES HEATING AND COOLING DEGREE DAYS.

RH INDICATES RELATIVE HUMIDITY

W/O INDICATES WEATHER AND OBSTRUCTIONS

S INDICATES SUNSHINE.

PR INDICATES PRESSURE.

CLOUDINESS ON PAGE 3 IS THE SUM OF THE CEILOMETER AND SATELLITE DATA NOT TO EXCEED EIGHT EIGHTHS (OKTAS).

GENERAL:

T INDICATES TRACE PRECIPITATION, AN AMOUNT GREATER THAN ZERO BUT LESS THAN THE LOWEST REPORTABLE VALUE.

+ INDICATES THE VALUE ALSO OCCURS ON EARLIER DATES.

BLANK ENTRIES DENOTE MISSING OR UNREPORTED DATA.

NORMALS ARE 30–YEAR AVERAGES (1961–1990).

ASOS INDICATES AUTOMATED SURFACE OBSERVING SYSTEM.

PM INDICATES THE LAST DAY OF THE PREVIOUS MONTH.

POR (PERIOD OF RECORD) BEGINS WITH THE JANUARY DATA MONTH AND IS THE NUMBER OF YEARS USED TO COMPUTE THE MEAN. INDIVIDUAL MONTHS WITHIN THE POR MAY BE MISSING.

WHEN THE POR FOR A NORMAL IS LESS THAN 30 YEARS, THE NORMAL IS PROVISIONAL AND IS BASED ON THE NUMBER OF YEARS INDICATED.

0.* OR * INDICATES THE VALUE OR MEAN–DAYS–WITH IS BETWEEN 0.00 AND 0.05.

CLOUDINESS FOR ASOS STATIONS DIFFERS FROM THE NON–ASOS OBSERVATION TAKEN BY A HUMAN OBSERVER. ASOS STATION CLOUDINESS IS BASED ON TIME–AVERAGED CEILOMETER DATA FOR CLOUDS AT OR BELOW 12,000 FEET AND ON SATELLITE DATA FOR CLOUDS ABOVE 12,000 FEET.

THE NUMBER OF DAYS WITH CLEAR, PARTLY CLOUDY, AND CLOUDY CONDITIONS FOR ASOS STATIONS IS THE SUM OF THE CEILOMETER AND SATELLITE DATA FOR THE SUNRISE TO SUNSET PERIOD.

GENERAL CONTINUED:

CLEAR INDICATES 0–2 OKTAS, PARTLY CLOUDY INDICATES 3–6 OKTAS, AND CLOUDY INDICATES 7 OR 8 OKTAS. WHEN AT LEAST ONE OF THE ELEMENTS (CEILOMETER OR SATELLITE) IS MISSING, THE DAILY CLOUDINESS IS NOT COMPUTED.

WIND DIRECTION IS RECORDED IN TENS OF DEGREES (2 DIGITS) CLOCKWISE FROM TRUE NORTH. "00" INDICATES CALM. "36" INDICATES TRUE NORTH.

RESULTANT WIND IS THE VECTOR AVERAGE OF THE SPEED AND DIRECTION.

AVERAGE TEMPERATURE IS THE SUM OF THE MEAN DAILY MAXIMUM AND MINIMUM TEMPERATURE DIVIDED BY 2.

SNOWFALL DATA COMPRISE ALL FORMS OF FROZEN PRECIPITATION, INCLUDING HAIL.

A HEATING (COOLING) DEGREE DAY IS THE DIFFERENCE BETWEEN THE AVERAGE DAILY TEMPERATURE AND 65 F.

DRY BULB IS THE TEMPERATURE OF THE AMBIENT AIR.

DEW POINT IS THE TEMPERATURE TO WHICH THE AIR MUST BE COOLED TO ACHIEVE 100 PERCENT RELATIVE HUMIDITY.

WET BULB IS THE TEMPERATURE THE AIR WOULD HAVE IF THE MOISTURE CONTENT WAS INCREASED TO 100 PERCENT RELATIVE HUMIDITY.

ON JULY 1, 1996, THE NATIONAL WEATHER SERVICE BEGAN USING THE "METAR" OBSERVATION CODE THAT WAS ALREADY EMPLOYED BY MOST OTHER NATIONS OF THE WORLD. THE MOST NOTICEABLE DIFFERENCE IN THIS ANNUAL PUBLICATION WILL BE THE CHANGE IN UNITS FROM TENTHS TO EIGHTS (OKTAS) FOR REPORTING THE AMOUNT OF SKY COVER.

HEATING DEGREE DAYS (base 65 F) 2001 LAS VEGAS, NV (LAS)
YEAR	JUL	AUG	SEP	OCT	NOV	DEC	JAN	FEB	MAR	APR	MAY	JUN	TOTAL
1972-73	0	0	0	108	453	727	744	428	437	132	12	0	3041
1973-74	0	0	0	42	349	576	738	443	188	82	13	0	2431
1974-75	0	0	0	55	300	634	607	446	340	249	37	0	2668
1975-76	0	0	0	73	354	516	553	339	357	124	1	0	2317
1976-77	0	0	0	39	212	569	593	297	374	45	56	0	2185
1977-78	0	0	0	3	226	399	522	356	168	91	16	0	1781
1978-79	0	0	1	2	324	676	737	458	270	66	18	0	2552
1979-80	0	0	0	44	395	546	474	335	328	108	32	0	2262
1980-81	0	0	0	82	255	374	426	344	263	29	2	0	1775
1981-82	0	0	0	74	214	497	594	398	301	98	9	0	2185
1982-83	0	0	10	84	429	631	564	364	263	198	21	0	2564
1983-84	0	0	0	3	297	524	548	424	216	111	0	0	2123
1984-85	0	0	0	127	363	641	629	487	308	41	0	0	2596
1985-86	0	0	1	31	393	512	404	270	125	57	11	0	1804
1986-87	0	0	14	53	268	586	622	375	316	40	1	0	2275
1987-88	0	0	0	18	342	689	612	357	225	83	33	0	2359
1988-89	0	0	0	0	291	581	647	425	118	23	16	0	2101
1989-90	0	0	0	70	224	519	606	449	172	12	0	0	2052
1990-91	0	0	0	23	290	761	597	247	376	57	25	2	2378
1991-92	0	0	0	77	297	552	584	308	248	7	0	0	2073
1992-93	0	0	0	16	364	655	591	410	143	32	3	8	2222
1993-94	0	0	0	33	398	573	480	455	93	60	1	0	2093
1994-95	0	0	0	35	465	537	537	170	230	90	18	6	2088
1995-96	0	0	0	22	151	490	504	287	169	22	11	0	1656
1996-97	0	0	0	138	249	524	512	368	115	117	0	0	2023
1997-98	0	0	0	57	259	583	500	426	270	166	23	0	2284
1998-99	0	0	0	39	296	525	444	337	143	188	5	6	1983
1999-00	0	0	0	11	184	499	412	325	195	16	3	0	1645
2000-01	0	0	0	80	436	474	570	421	175	114	2	0	2272
2001-	0	0	0	0	204	602

COOLING DEGREE DAYS (base 65 F) 2001 LAS VEGAS, NV (LAS)
YEAR	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANNUAL
1972	0	2	66	80	308	597	876	675	398	69	0	0	3071
1973	0	0	0	54	382	612	833	708	424	134	8	0	3155
1974	0	0	24	43	394	731	744	713	559	195	0	0	3403
1975	0	0	2	2	276	570	792	704	508	117	2	0	2973
1976	0	0	2	57	404	500	687	641	419	93	6	0	2809
1977	0	0	0	161	149	694	858	781	476	210	3	0	3332
1978	0	0	17	40	277	672	841	752	425	268	8	0	3300
1979	0	0	0	104	346	625	813	656	614	229	0	0	3387
1980	0	0	0	68	160	575	842	788	498	211	15	0	3157
1981	0	0	5	205	296	721	866	781	531	64	12	0	3481
1982	0	0	2	70	281	501	721	699	404	30	0	0	2708
1983	0	0	2	9	269	541	735	589	534	94	10	0	2783
1984	0	0	3	61	496	563	724	641	508	74	1	0	3071
1985	0	0	0	143	377	678	844	778	319	110	2	0	3251
1986	0	20	69	98	379	693	707	821	332	59	0	0	3178
1987	0	0	0	148	302	645	685	729	495	211	0	0	3215
1988	0	0	16	64	300	615	864	685	434	312	31	0	3321
1989	0	11	74	259	351	614	887	687	456	143	0	0	3482
1990	0	0	42	134	302	634	810	713	516	163	0	0	3314
1991	0	0	0	42	187	524	788	714	515	307	12	0	3089
1992	0	0	0	180	402	552	742	798	571	206	3	0	3454
1993	0	0	21	114	381	537	765	737	494	166	0	0	3215
1994	0	0	31	145	369	768	883	870	551	108	0	0	3725
1995	0	0	13	91	211	490	856	880	570	168	2	0	3281
1996	0	3	16	129	402	665	883	841	471	201	0	0	3611
1997	0	0	48	136	522	584	727	805	494	137	4	0	3457
1998	0	0	18	55	186	457	834	842	456	95	0	0	2943
1999	0	0	13	74	333	620	726	719	508	221	3	0	3217
2000	0	0	3	208	498	719	851	799	509	158	0	0	3745
2001	0	0	47	122	541	692	792	843	609	231	17	0	3894

REFERENCE NOTES:

PAGE 1:

THE TEMPERATURE GRAPH SHOWS NORMAL MAXIMUM AND NORMAL MINIMUM DAILY TEMPERATURES (SOLID CURVES) AND THE ACTUAL DAILY HIGH AND LOW TEMPERATURES (VERTICAL BARS).

PAGE 2 AND 3:

H/C INDICATES HEATING AND COOLING DEGREE DAYS.

RH INDICATES RELATIVE HUMIDITY

W/O INDICATES WEATHER AND OBSTRUCTIONS

S INDICATES SUNSHINE.

PR INDICATES PRESSURE.

CLOUDINESS ON PAGE 3 IS THE SUM OF THE CEILOMETER AND SATELLITE DATA NOT TO EXCEED EIGHT EIGHTHS (OKTAS).

GENERAL:

T INDICATES TRACE PRECIPITATION, AN AMOUNT GREATER THAN ZERO BUT LESS THAN THE LOWEST REPORTABLE VALUE.

+ INDICATES THE VALUE ALSO OCCURS ON EARLIER DATES.

BLANK ENTRIES DENOTE MISSING OR UNREPORTED DATA.

NORMALS ARE 30–YEAR AVERAGES (1961–1990).

ASOS INDICATES AUTOMATED SURFACE OBSERVING SYSTEM.

PM INDICATES THE LAST DAY OF THE PREVIOUS MONTH.

POR (PERIOD OF RECORD) BEGINS WITH THE JANUARY DATA MONTH AND IS THE NUMBER OF YEARS USED TO COMPUTE THE MEAN. INDIVIDUAL MONTHS WITHIN THE POR MAY BE MISSING.

WHEN THE POR FOR A NORMAL IS LESS THAN 30 YEARS, THE NORMAL IS PROVISIONAL AND IS BASED ON THE NUMBER OF YEARS INDICATED.

0.* OR * INDICATES THE VALUE OR MEAN–DAYS–WITH IS BETWEEN 0.00 AND 0.05.

CLOUDINESS FOR ASOS STATIONS DIFFERS FROM THE NON–ASOS OBSERVATION TAKEN BY A HUMAN OBSERVER. ASOS STATION CLOUDINESS IS BASED ON TIME–AVERAGED CEILOMETER DATA FOR CLOUDS AT OR BELOW 12,000 FEET AND ON SATELLITE DATA FOR CLOUDS ABOVE 12,000 FEET.

THE NUMBER OF DAYS WITH CLEAR, PARTLY CLOUDY, AND CLOUDY CONDITIONS FOR ASOS STATIONS IS THE SUM OF THE CEILOMETER AND SATELLITE DATA FOR THE SUNRISE TO SUNSET PERIOD.

GENERAL CONTINUED:

CLEAR INDICATES 0–2 OKTAS, PARTLY CLOUDY INDICATES 3–6 OKTAS, AND CLOUDY INDICATES 7 OR 8 OKTAS. WHEN AT LEAST ONE OF THE ELEMENTS (CEILOMETER OR SATELLITE) IS MISSING, THE DAILY CLOUDINESS IS NOT COMPUTED.

WIND DIRECTION IS RECORDED IN TENS OF DEGREES (2 DIGITS) CLOCKWISE FROM TRUE NORTH. "00" INDICATES CALM. "36" INDICATES TRUE NORTH.

RESULTANT WIND IS THE VECTOR AVERAGE OF THE SPEED AND DIRECTION.

AVERAGE TEMPERATURE IS THE SUM OF THE MEAN DAILY MAXIMUM AND MINIMUM TEMPERATURE DIVIDED BY 2.

SNOWFALL DATA COMPRISE ALL FORMS OF FROZEN PRECIPITATION, INCLUDING HAIL.

A HEATING (COOLING) DEGREE DAY IS THE DIFFERENCE BETWEEN THE AVERAGE DAILY TEMPERATURE AND 65 F.

DRY BULB IS THE TEMPERATURE OF THE AMBIENT AIR.

DEW POINT IS THE TEMPERATURE TO WHICH THE AIR MUST BE COOLED TO ACHIEVE 100 PERCENT RELATIVE HUMIDITY.

WET BULB IS THE TEMPERATURE THE AIR WOULD HAVE IF THE MOISTURE CONTENT WAS INCREASED TO 100 PERCENT RELATIVE HUMIDITY.

ON JULY 1, 1996, THE NATIONAL WEATHER SERVICE BEGAN USING THE "METAR" OBSERVATION CODE THAT WAS ALREADY EMPLOYED BY MOST OTHER NATIONS OF THE WORLD. THE MOST NOTICEABLE DIFFERENCE IN THIS ANNUAL PUBLICATION WILL BE THE CHANGE IN UNITS FROM TENTHS TO EIGHTS (OKTAS) FOR REPORTING THE AMOUNT OF SKY COVER.