2001 Los Angeles, California Downtown L.A./USC Campus (CQT)

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2001 LOS ANGELES, CALIFORNIA Downtown L.A./USC Campus (CQT)

The climate of Los Angeles is normally pleasant and mild through the year. The Pacific Ocean is the primary moderating influence. The coastal mountain ranges lying along the north and east sides of the Los Angeles coastal basin act as a buffer against extremes of summer heat and winter cold occurring in desert and plateau regions in the interior. A variable balance between mild sea breezes, and either hot or cold winds from the interior, results in some variety in weather conditions, but temperature and humidity are usually well within the limits of human comfort. An important, and somewhat unusual, aspect of the climate of the Los Angeles metropolitan area is the pronounced difference in temperature, humidity, cloudiness, fog, rain, and sunshine over fairly short distances.

These differences are closely related to the distance from, and elevation above, the Pacific Ocean. Both high and low temperatures become more extreme and the average relative humidity becomes lower as one goes inland and up foothill slopes. Relative humidity is frequently high near the coast, but may be quite low along the foothills. During periods of high temperatures, the relative humidity is usually below normal so that discomfort is rare, except for infrequent periods when high temperatures and high humidities occur together.

Like other Pacific Coast areas, most rainfall comes during the winter with nearly 85 percent of the annual total occurring from November through March, while summers are practically rainless. As in many semi–arid regions, there is a marked variability in monthly and seasonal totals. Precipitation generally increases with distance from the ocean, from a yearly total of around 12 inches in coastal sections to the south of the city to over 20 inches in foothill areas. Destructive flash floods occasionally develop in and below some mountain canyons. Snow is often visible on nearby mountains in the winter, but is extremely rare in the coastal basin. Thunderstorms are infrequent.

Prevailing winds are from the west during the spring, summer, and early autumn, with northeasterly wind predominating the remainder of the year. At times, the lack of air movement, combined with a frequent and persistent temperature inversion, is associated with concentrations of air pollution in the Los Angeles coastal basin and some adjacent areas. In fall, winter, and early spring months, occasional foehn–like descending Santa Ana winds come from the northeast over ridges and through passes in the coastal mountains. These Santa Ana winds may pick up considerable amounts of dust and reach speeds of 35 to 50 mph in north and east sections of the city, with higher speeds in outlying areas to the north and east, but rarely reach coastal portions of the city.

Sunshine, fog, and clouds depend a great deal on topography and distance from the ocean. Low clouds are common at night and in the morning along the coast during spring and summer, but form later and clear earlier near the foothills so that annual cloudiness and fog frequencies are greatest near the ocean, and sunshine totals are highest on the inland side of the city. The sun shines about 75 percent of daytime hours at the Civic Center. Light fog may accompany the usual night and morning low clouds, but dense fog is more likely to occur during the night and early morning hours of the winter months.

NORMALS, MEANS, AND EXTREMES

LOS ANGELES, CA (CQT)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 93134

34 01′ 40″ N  118 17′ 45″ W  GRND: 182  BARO: 185  PACIFIC (UTC + 8)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3067.769.469.572.373.978.384.084.582.779.072.467.875.1
MEAN DAILY MAXIMUM8166.567.668.771.273.477.282.783.582.177.873.267.774.3
HIGHEST DAILY MAXIMUM6195959810610211210710511010810091112
YEAR OF OCCURRENCE197119951988198919671990198519831988198719661979JUN 1990
MEAN OF EXTREME MAXS.8180.982.484.087.989.089.993.094.296.794.487.581.788.5
NORMAL DAILY MINIMUM3048.950.651.854.257.761.164.565.764.660.353.548.856.8
MEAN DAILY MINIMUM8148.449.951.153.756.859.863.364.363.059.053.549.556.0
LOWEST DAILY MINIMUM6128343539464954535141383028
YEAR OF OCCURRENCE194919891976197519641999195219431948197119781978JAN 1949
MEAN OF EXTREME MINS.8139.942.343.846.851.254.758.859.857.252.045.140.949.4
NORMAL DRY BULB3058.360.160.763.365.869.774.375.173.769.763.058.366.0
MEAN DRY BULB8157.458.760.062.565.168.473.073.972.668.463.358.665.2
MEAN WET BULB249.450.253.955.260.262.963.965.461.955.048.1
MEAN DEW POINT242.544.949.450.255.759.160.262.059.149.838.3
NORMAL NO. DAYS WITH:
MAXIMUM 90300.10.20.31.11.32.14.15.35.93.40.7*24.5
MAXIMUM 32300.00.00.00.00.00.00.00.00.00.00.00.00.0
MINIMUM 3230*0.00.00.00.00.00.00.00.00.00.00.10.1
MINIMUM 0300.00.00.00.00.00.00.00.00.00.00.00.00.0
H/CNORMAL HEATING DEG. DAYS3022217016912872350010171052261154
NORMAL COOLING DEG. DAYS30143236779717629331627116245181537
RHNORMAL (PERCENT)
HOUR 04 LST
HOUR 10 LST
HOUR 16 LST
HOUR 22 LST
SPERCENT POSSIBLE SUNSHINE3269727370666582837973747173
W/OMEAN NO. DAYS WITH:
HEAVY FOG (VISBY 1/4 MI)261.61.71.11.20.60.60.50.81.32.42.42.116.3
THUNDERSTORMS260.51.10.90.80.20.10.20.40.40.30.60.76.2
CLOUDINESSMEAN:
SUNRISE–SUNSET (OKTAS)343.53.83.83.83.83.42.22.12.43.03.03.43.2
MIDNIGHT–MIDNIGHT (OKTAS)
MEAN NO. DAYS WITH:
CLEAR3414.312.412.912.011.413.620.922.418.416.116.515.0185.9
PARTLY CLOUDY348.16.99.39.811.810.58.97.48.49.37.48.0105.8
CLOUDY348.59.08.78.27.85.91.11.23.35.66.18.073.4
PRMEAN STATION PRESSURE(IN)229.9229.8729.8029.8129.7329.7329.7429.7229.6929.7729.8629.9029.79
MEAN SEA–LEVEL PRES. (IN)230.1130.0729.9930.0129.9229.9229.9429.9229.9730.0630.10
WINDSMEAN SPEED (MPH)266.46.66.66.46.15.55.15.05.25.35.86.05.8
PREVAIL. DIR (TENS OF DEGS)
MAXIMUM 2–MINUTE:
SPEED (MPH)221152016161312121315151621
DIR. (TENS OF DEGS)33200328252626262325253333
YEAR OF OCCURRENCE200020002000200120002001200120012000200020002001JAN 2000
MAXIMUM 5–SECOND:
SPEED (MPH)229283025252018181824242330
DIR. (TENS OF DEGS)33250325272526262527242603
YEAR OF OCCURRENCE200020002000200120002000200120002000200020002001MAR 2000
PRECIPITATIONNORMAL (IN)302.923.072.611.030.190.030.010.140.450.311.982.0314.77
MAXIMUM MONTHLY (IN)6114.9413.688.376.023.100.980.182.262.822.379.686.5714.94
YEAR OF OCCURRENCE196919981983196519981999198619771976198719651971JAN 1969
MINIMUM MONTHLY (IN)610.00T0.000.000.000.000.000.000.000.000.000.000.00
YEAR OF OCCURRENCE197619511959197919811982198319821980198019801990DEC 1990
MAXIMUM IN 24 HOURS (IN)616.114.023.792.052.410.760.182.221.951.774.073.926.11
YEAR OF OCCURRENCE195619441978195619771993198619771986198319701965JAN 1956
NORMAL NO. DAYS WITH:
PRECIPITATION 0.01305.35.36.23.41.00.50.20.71.81.83.64.434.2
PRECIPITATION 1.00301.01.20.70.20.10.00.0*0.1*0.60.64.5
SNOWFALLNORMAL (IN)300.00.00.00.00.00.00.00.00.00.00.00.00.0
MAXIMUM MONTHLY (IN)560.3T0.00.00.00.00.00.00.00.00.0T0.3
YEAR OF OCCURRENCE194919511947JAN 1949
MAXIMUM IN 24 HOURS (IN)560.3T0.00.00.00.00.00.00.00.00.0T0.3
YEAR OF OCCURRENCE194919511947JAN 1949
MAXIMUM SNOW DEPTH (IN)560000000000000
YEAR OF OCCURRENCE
NORMAL NO. DAYS WITH:
SNOWFALL 1.0300.00.00.00.00.00.00.00.00.00.00.00.00.0
PRECIPITATION (inches) 2001 LOS ANGELES, CALIFORNIA CA (CQT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720.000.13T0.030.030.070.000.350.020.293.262.366.54
19734.397.892.700.00T0.000.000.000.000.121.680.6717.45
19748.350.143.780.100.080.000.000.000.000.580.073.5916.69
19750.123.544.831.530.090.000.000.000.000.270.000.3210.70
19760.003.711.810.840.050.220.000.082.820.240.490.7511.01
19772.840.171.890.003.030.000.002.260.000.000.084.7014.97
19787.708.918.021.770.000.000.000.000.390.052.281.4530.57
19796.593.065.850.000.000.000.000.01T0.770.210.5117.00
19807.5012.754.790.310.130.000.000.000.000.000.000.8526.33
19812.021.484.100.530.000.000.000.000.020.491.800.4810.92
19822.170.703.541.390.120.000.000.000.840.194.411.0514.41
19836.494.378.375.160.360.010.000.791.990.752.523.2334.04
19840.170.000.280.690.000.010.000.400.230.151.445.538.90
19850.712.841.290.000.230.000.000.000.190.422.910.338.92
19862.196.105.270.450.000.000.180.001.970.530.940.3718.00
19871.391.220.950.060.000.050.010.000.092.371.131.849.11
19881.651.720.263.410.000.000.000.050.040.000.703.8011.63
19890.731.900.810.000.050.000.000.000.350.430.290.004.56
19901.243.120.170.581.170.000.000.020.000.000.190.006.49
19911.694.135.920.030.000.010.130.000.090.370.003.2215.59
19921.747.967.120.330.040.000.080.000.000.700.004.6822.65
199311.776.612.740.000.020.760.000.000.000.160.660.7823.50
19940.333.211.860.830.280.000.000.000.000.190.611.358.66
199512.561.306.980.580.180.600.020.000.000.000.091.3423.65
19963.164.942.160.710.040.000.000.000.001.061.594.0917.75
19975.580.080.000.000.000.000.000.000.450.002.062.5210.69
19984.1213.684.060.973.100.050.000.000.010.001.320.5427.85
19991.850.561.242.570.020.98T0.00T0.000.440.408.06
20000.885.542.821.49T0.000.000.070.150.98TT11.93
20015.598.871.171.110.00TT0.000.000.061.421.3819.60
POR=124 YRS3.493.232.451.090.250.050.010.100.310.301.671.8914.84
AVERAGE TEMPERATURE (F) 2001 LOS ANGELES, CALIFORNIA CA (CQT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197255.560.363.763.967.672.278.077.472.367.262.258.166.5
197356.460.057.963.165.872.072.473.670.068.860.059.965.0
197455.259.259.664.765.772.274.172.373.267.664.056.265.3
197557.655.855.756.062.765.772.571.974.066.461.257.063.0
197659.456.458.457.864.371.172.671.672.670.766.960.465.2
197758.163.156.963.761.969.274.275.671.869.066.360.865.9
197858.158.963.260.868.671.873.473.776.070.358.453.265.5
197953.355.057.962.765.471.572.172.977.468.764.663.265.4
198060.964.660.964.863.271.877.176.372.671.565.363.767.7
198161.864.362.066.068.977.477.278.375.068.565.062.168.9
198257.164.059.362.264.465.374.075.173.970.961.758.165.5
198361.963.063.963.270.770.775.980.879.174.263.559.868.9
198461.261.965.665.372.472.278.776.481.368.561.057.268.5
198557.560.459.366.866.373.579.275.771.871.360.461.767.0
198665.962.464.566.468.171.273.276.068.869.466.460.167.7
198757.260.361.267.868.169.770.873.075.271.962.954.466.0
198858.362.964.964.167.267.974.372.972.269.761.957.166.1
198956.356.462.467.966.269.875.172.874.569.266.762.766.7
199059.458.061.765.766.974.377.374.076.073.265.657.567.5
199159.263.556.864.263.967.171.073.173.672.166.259.665.9
199260.362.360.869.669.070.475.978.976.670.465.156.568.0
199357.358.364.567.068.972.473.074.474.371.264.660.867.2
199462.259.364.764.365.174.473.680.576.570.459.959.967.6
199558.465.362.664.864.069.075.877.577.071.567.160.967.8
199660.961.363.068.869.071.975.177.273.567.064.359.767.6
199758.761.065.165.772.771.073.277.679.871.165.258.968.3
199858.857.161.962.264.268.876.279.973.669.062.459.166.1
199960.859.956.959.463.366.871.871.469.271.561.858.164.2
200058.557.659.564.167.771.272.374.772.765.159.058.965.1
200154.454.760.459.967.370.871.072.071.468.262.056.464.0
POR=124 YRS56.457.659.161.464.067.772.072.871.467.262.457.864.2

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 LOS ANGELES, CALIFORNIA CA (CQT)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972–730001497230266136214773221068
1973–740018156174300160171543211057
1974–75000257326824325428326275211504
1975–760003113224719024621521550121338
1976–7700006213821586247571081914
1977–780001451132209174102122240828
1978–790007209361354274226804661563
1979–800001591141286012379754643
1980–810002418510391974310463
1981–820001158102238581841134116821
1982–83000311720513473686820670
1983–8400009915814099295950589
1984–85000412923922516217940210999
1985–86000016313142125923270592
1986–8700821415124114013131190737
1987–880003913232168281883011925
1988-89001298258270271104362751072
1989-9000022710217320613026162684
1990-910000422441836324874722928
1991–920002346168159114125100636
1992–9300014925623518168906805
1993–940000451361061536160350596
1994–9500001581602116291595214807
1995–9600016132146125831631513
1996–970003176158196120614900691
1997–98000071193185216118130363952
1998–9900017920013714424521166321115
1999–000021952071972111666190949
2000–0100036179186321293147164501331
2001–000397260
COOLING DEGREE DAYS (base 65 F) 2001 LOS ANGELES, CALIFORNIA CA (CQT)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720427341222234093912258921251570
197392025642202362721571339211148
197435851582232882352541155321295
197521000114824122127782264931
197622320103220324521223318512321290
1977739323181352933342101489681314
1978085221452122692773381771701497
19790014176720922925237912453621406
198010543822621538035723321056531679
19811275138113238038742230612467172016
1982036153633322863222751942501254
1983442341211851743424954322926042113
1984291456732402224333604961231362065
1985041101006826444733921020331351748
1986775683801101942613491321456561558
1987618211201211471862573122213611446
19881330846810710729725222315414201369
1989837311317315431825129013985411558
1990101636548129138828733626268201849
199182805443721912602652508861265
1992174411461321683474353531755901877
199360597712923225429928719938121592
19942505947472882724883541789101777
1995137624613114234139436921277121752
19962526281341342153203862661016001695
1997714727924518826040245019685112009
19980029531812535646826613211241482
1999148049239021720213620870954
2000524399819223330823945231170
2001113918851801912262001101431050
SNOWFALL (inches) 2001 LOS ANGELES, CALIFORNIA CA (CQT)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1970–710.00.00.00.00.00.00.00.00.00.00.00.00.0
1971–720.00.00.00.00.00.00.00.00.00.00.00.00.0
1972–730.00.00.00.00.00.00.00.00.00.00.00.00.0
1973–740.00.00.00.00.00.00.00.00.00.00.00.00.0
1974–750.00.00.00.00.00.00.00.00.00.00.00.00.0
1975–760.00.00.00.00.00.00.00.00.00.00.00.00.0
1976–770.00.00.00.00.00.00.00.00.00.00.00.00.0
1977–780.00.00.00.00.00.00.00.00.00.00.00.00.0
1978–790.00.00.00.00.00.00.00.00.00.00.00.00.0
1979–800.00.00.00.00.00.00.00.00.00.00.00.00.0
1980–810.00.00.00.00.00.00.00.00.00.00.00.00.0
1981–820.00.00.00.00.00.00.00.00.00.00.00.00.0
1982–830.00.00.00.00.00.00.00.00.00.00.00.00.0
1983–840.00.00.00.00.00.00.00.00.00.0
1984–85
1996–97
1997–98
1998–99
1999–00
2000–01
2001–
POR=43 YRS0.00.00.00.00.0T0.0T0.00.00.00.0T

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