2001 St. Louis, Missouri (STL)

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2001 ST. LOUIS, MISSOURI (STL)

St Louis is located at the confluence of the Missouri and Mississippi Rivers and near the geographical center of the United States. Its position in the middle latitudes allows the area to be affected by warm moist air that originates in the Gulf of Mexico, as well as cold air masses that originate in Canada. The alternate invasion of these airmasses produces a wide variety of weather conditions, and allows the region to enjoy a true four–season climate.

During the summer months, air originating from the Gulf of Mexico tends to dominate the area, producing warm and humid conditions. Since 1870, records indicate that temperatures of 90 degrees or higher occur on about 35–40 days per year. Extrmely hot days (100 degrees or more) are expected on no more than five days per year.

Winters are brisk and stimulating, but prolonged periods of extremely cold weather are rare. Records show that temperatures drop to zero or below an average of 2 or 3 days per year, and temperatures as cold as 32 degrees or lower occur less than 25 days in most years. Snowfall has averaged a little over 18 inches per winter season, and snowfall of an inch or less is received on 5 to 10 days in most years.

Normal annual precipitation for St. Louis is a little less than 34 inches. The three winter months are the driest, with an average total of about 6 inches of precipitation. The spring months of March through May are normally the wettest with normal total rainfall of just under 10.5 inches. It is not unusual to have extended dry periods of one to two weeks during growing season.

Thunderstorms normally occur on between 40 and 50 days per year. During any year, there are usually a few of these thunderstorms that are severe, and produce large hail and damaging winds. Tornadoes have produced extensive damage and loss of life in the St. Louis area.

NORMALS, MEANS, AND EXTREMES

ST. LOUIS, MO (STL)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 13994

38 45′ 09″ N  90 22′ 25″ W  GRND:  707  BARO:  710  CENTRAL  (UTC + 6)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3037.742.654.666.976.185.289.387.379.968.554.741.765.4
MEAN DAILY MAXIMUM5638.644.154.066.876.185.188.987.480.169.154.342.765.6
HIGHEST DAILY MAXIMUM447685899394102107107104948576107
YEAR OF OCCURRENCE197019721985198919961988198019841984196319891970AUG 1984
MEAN OF EXTREME MAXS.5663.568.679.186.689.495.498.698.393.486.175.066.483.4
NORMAL DAILY MINIMUM3020.825.135.546.456.065.770.467.960.548.337.726.046.7
MEAN DAILY MINIMUM5621.625.934.445.955.765.269.467.659.447.936.326.346.3
LOWEST DAILY MINIMUM44-18-12-5223143514736231-16-18
YEAR OF OCCURRENCE198519961960197519761969197219861974197619641989JAN 1985
MEAN OF EXTREME MINS.560.26.316.129.940.552.058.356.343.832.519.16.530.1
NORMAL DRY BULB3029.333.945.156.766.175.479.877.670.258.446.233.956.1
MEAN DRY BULB5630.135.044.256.365.975.279.277.669.858.545.134.556.0
MEAN WET BULB1728.532.940.249.959.667.671.470.262.352.241.531.950.7
MEAN DEW POINT1722.826.432.842.653.562.866.965.957.245.835.126.144.8
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.00.41.38.015.111.64.40.20.00.041.0
MAXIMUM 323011.47.01.30.00.00.00.00.00.00.00.67.027.3
MINIMUM 323026.721.313.52.80.10.00.00.00.01.711.023.3100.4
MINIMUM 0302.30.5*0.00.00.00.00.00.00.00.01.13.9
H/CNORMAL HEATING DEG. DAYS301107871617266111000212375649644758
NORMAL COOLING DEG. DAYS300001714531245939117733001534
RHNORMAL (PERCENT)3073726864666768707269727670
HOUR 00 LST3077777470757677808176777977
HOUR 06 LST3082828178828385888984838383
HOUR 12 LST3065645954555656575856636859
HOUR 18 LST3068665953555556586060677361
SPERCENT POSSIBLE SUNSHINE3750525456596669646360464357
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)442.21.61.50.60.60.30.20.30.50.71.12.011.6
THUNDERSTORMS440.80.83.05.86.77.47.26.53.62.51.70.646.6
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)485.45.35.45.25.14.84.44.24.14.04.95.34.8
MIDNIGHT-MIDNIGHT (OKTAS)325.05.15.14.94.74.33.83.83.93.94.85.14.5
MEAN NO. DAYS WITH:
CLEAR487.36.66.56.97.17.19.310.111.412.38.67.1100.3
PARTLY CLOUDY486.66.58.08.29.511.011.311.18.27.56.66.6101.1
CLOUDY4817.115.116.514.914.411.910.49.810.411.214.917.3163.9
PRMEAN STATION PRESSURE(IN)2929.5329.5029.4029.3729.3529.3729.3929.4229.4529.4629.4729.5129.43
MEAN SEA-LEVEL PRES. (IN)1730.1430.1230.0429.9529.9529.9429.9830.0130.0330.0730.0830.1630.04
WINDSMEAN SPEED (MPH)5110.510.711.611.39.48.77.97.48.18.710.210.39.6
PREVAIL. DIR (TENS OF DEGS)3230303030181818181818303030
MAXIMUM 2-MINUTE:
SPEED (MPH)536393744414337393343413844
DIR. (TENS OF DEGS)31232625292730273231243125
YEAR OF OCCURRENCE199719991998199720002001200120002000200119981998APR 1997
MAXIMUM 5-SECOND:
SPEED (MPH)543545259515148484051534759
DIR. (TENS OF DEGS)35233027272634273430243027
YEAR OF OCCURRENCE200019992001199820002001199920002000200119982000APR 1998
PRECIPITATIONNORMAL (IN)301.812.123.583.503.973.723.852.853.122.683.283.0337.51
MAXIMUM MONTHLY (IN)445.384.686.6710.3212.929.4310.716.449.167.129.957.8212.92
YEAR OF OCCURRENCE197519861978199419951985198119701993198419851982MAY 1995
MINIMUM MONTHLY (IN)440.100.251.090.991.020.440.600.08T0.210.440.32T
YEAR OF OCCURRENCE198619631966197719721991197019711979197519691958SEP 1979
MAXIMUM IN 24 HOURS (IN)442.432.602.954.916.553.593.473.173.502.703.714.036.55
YEAR OF OCCURRENCE197519991977197919952000198219931986198619851982MAY 1995
NORMAL NO. DAYS WITH:
PRECIPITATION 0.01308.48.411.411.210.59.58.57.97.98.49.59.7111.3
PRECIPITATION 1.00300.30.40.60.61.11.11.20.80.80.60.90.89.2
SNOWFALLNORMAL (IN)306.55.33.70.60.00.00.00.00.0T1.54.622.2
MAXIMUM MONTHLY (IN)6523.920.822.36.50.6TT0.00.0T11.326.326.3
YEAR OF OCCURRENCE1977199319601971199319931997199319511973DEC 1973
MAXIMUM IN 24 HOURS (IN)6513.911.710.76.10.6TT0.00.0T10.312.013.9
YEAR OF OCCURRENCE1982199319891971199319931997199319511973JAN 1982
MAXIMUM SNOW DEPTH (IN)531320176000000101220
YEAR OF OCCURRENCE197819821978197119511973FEB 1982
NORMAL NO. DAYS WITH:
SNOWFALL 1.0301.91.50.80.20.00.00.00.00.00.00.41.46.2
PRECIPITATION (inches) 2001 ST. LOUIS, MO (STL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720.770.742.934.491.021.193.102.696.211.475.593.5433.74
19731.401.045.814.253.924.232.852.463.522.333.654.3639.82
19743.514.172.582.405.903.450.905.052.501.513.151.7136.83
19755.383.594.084.563.233.782.565.442.480.212.622.2840.21
19760.831.084.281.373.902.322.281.270.903.370.731.1323.46
19772.382.476.280.992.135.474.285.343.643.764.332.3443.41
19781.701.606.673.213.692.396.030.763.102.284.471.8137.71
19791.951.483.637.471.621.673.672.26T1.812.071.8529.48
19800.631.543.981.543.402.193.562.723.122.891.250.6627.48
19810.642.182.973.406.795.8210.713.311.173.812.712.0145.52
19824.901.372.882.554.855.967.915.275.272.303.897.8254.97
19830.720.953.547.306.324.321.232.241.245.407.793.7544.80
19840.843.435.376.295.192.740.760.648.887.125.504.8951.65
19850.533.775.183.603.309.435.233.660.431.969.953.6950.73
19860.104.681.221.232.424.432.612.227.995.341.581.0634.88
19871.981.402.161.742.003.595.045.561.621.744.097.4638.38
19883.302.274.731.151.441.973.022.311.991.866.653.2433.93
19892.581.434.532.104.112.344.593.001.690.950.590.6928.60
19901.423.532.663.079.593.023.342.840.784.963.366.5245.09
19911.520.983.203.273.870.445.180.982.985.703.262.1033.48
19921.121.893.452.461.451.194.313.452.981.216.323.6633.49
19933.542.753.316.163.947.125.064.789.162.614.851.4854.76
19942.091.511.2710.321.722.161.423.761.182.854.901.5234.70
19954.391.333.193.3312.922.962.164.520.742.011.282.8541.68
19963.270.523.067.974.343.726.331.572.862.676.500.8643.67
19972.744.142.852.663.052.001.443.362.732.052.361.8531.23
19982.882.936.004.633.626.906.392.351.862.512.720.8343.62
19995.103.522.403.722.205.264.221.951.092.040.721.8434.06
20001.233.111.881.845.848.222.253.642.622.602.791.3537.37
20011.122.481.453.012.813.604.001.992.815.503.063.4635.29
POR=131 YRS2.202.313.323.754.134.063.442.893.072.712.822.2936.99
AVERAGE TEMPERATURE (F) 2001 ST. LOUIS, MO (STL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197229.934.345.056.166.473.477.576.371.154.839.830.454.6
197332.634.550.953.761.774.678.776.970.060.747.030.055.9
197429.836.148.157.565.069.579.874.562.357.844.034.054.9
197533.232.039.053.467.674.977.877.964.759.048.335.555.3
197628.143.548.856.560.872.779.574.368.250.937.028.554.1
197715.134.849.660.871.174.781.276.470.755.544.730.655.4
197819.621.137.956.263.674.478.576.473.155.647.535.053.2
197916.623.144.152.965.576.579.278.470.859.244.538.754.1
198031.427.941.054.566.975.585.083.572.555.946.436.656.4
198131.236.846.763.160.775.778.776.169.255.748.731.156.1
198222.528.645.351.570.770.679.375.268.058.346.341.654.8
198332.338.144.550.362.375.383.584.272.059.748.220.555.9
198428.340.437.154.163.279.578.380.768.261.844.340.756.4
198522.630.549.560.467.671.679.374.770.961.446.527.355.2
198634.934.549.260.868.278.382.874.073.358.341.535.457.6
198730.640.148.656.972.677.981.078.970.553.849.138.058.2
198829.230.545.257.169.077.781.682.772.553.947.237.257.0
198941.228.245.057.764.374.879.377.867.461.347.124.155.7
199042.941.349.855.763.677.280.277.974.158.152.734.759.0
199129.341.750.161.573.079.980.979.772.460.542.439.259.2
199237.042.748.557.865.173.879.073.469.259.444.335.757.2
199332.131.741.554.266.475.181.980.466.456.143.937.255.6
199426.835.047.757.765.079.079.576.670.261.552.141.557.7
199531.136.449.056.864.775.681.383.968.060.942.733.857.0
199629.437.441.054.668.674.675.877.667.258.139.035.554.9
199726.738.147.650.961.773.680.276.070.259.142.035.155.1
199836.442.643.255.371.275.578.979.175.060.249.537.258.7
199931.342.542.858.666.874.982.976.569.758.852.638.358.0
200033.042.949.155.269.072.977.680.469.661.341.321.656.2
200130.535.141.563.168.774.180.779.668.857.753.139.957.7
POR=128 YRS31.235.044.556.266.075.279.577.670.158.845.535.056.2

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 ST. LOUIS, MO (STL)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-732029317751106999784943034812104913
1973-74003118253810771083804539253101214629
1974-75001272426259549799198033534815051
1975-7620110228498910113761950528815804455
1976-770024456832112515418394711903635517
1977-78001129160110591401122384027515855864
1978-790024292528923149611676443648005518
1979-800016223610810103510717403315404890
1980-810030305553877103978456912716804452
1981-8200352984831048130810156034079115217
1982-830049261569721100874563243711774546
1983-8400581924981376113370586034211505279
1984-8500103151616746130896048720042104623
1985-86006414555011599298505061944404441
1986-870111222169991010626915012671004384
1987-88001234649083011029956102411734646
1988-89005354528854730102962529312844550
1989-90007318353612616796574963278594306
1990-91302425037593411016484741542103984
1991-9200671916747968596425092649554102
1992-930346204615902101492772632752134829
1993-94005829262885211798335312618414719
1994-95003315538872210457944882608803973
1995-960065167664961109679773532267144888
1996-970057235776908118074653041814254997
1997-98001327168492288062168929319244416
1998-9900117546085910386266792144174100
1999-0000412263708269856384902973683917
2000-0100571767091338106383172115447135109
2001-0050246352772
COOLING DEGREE DAYS (base 65 F) 2001 ST. LOUIS, MO (STL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
1972005351292683943582199001417
1973001172529443537518757401395
19740024361091644633005225201175
19750021213330840540611051401431
1976008383423945829812925001229
1977002692313025093601904001667
19780071712029542636027610801519
1979002910235444642019550001578
19800002312032062658026231201964
1981007774232743135316613101417
19820007191186453322146631541387
198300334132257860327436201862
1984000246744242349320257211711
198500147012821445131024543201477
198600257515040756129826721001804
19870003225139350143918352001824
19880041014438952155623816001878
198900118011130545040315175601592
199000305547382480408304411201759
199100195627745249846329558302121
19920075410427744026818236001368
1993001910232052948310723001574
1994004489042845336519453701642
1995000228532251059516447001745
19960501618830934240213225001419
199700114426847734917399001412
19980021721734743944630533231820
19990002810430956336419037501600
2000056816725139848320269501594
200100010616629349245716729211713
SNOWFALL (inches) 2001 ST. LOUIS, MO (STL)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.00.05.21.02.23.00.20.20.00.011.8
1973-740.00.00.00.00.026.34.24.57.40.00.00.042.4
1974-750.00.00.00.01.21.54.112.16.3T0.00.025.2
1975-760.00.00.00.07.63.94.54.54.80.00.00.025.3
1976-770.00.00.00.00.35.223.96.70.10.10.00.036.3
1977-780.00.00.00.06.711.722.99.315.40.00.00.066.0
1978-790.00.00.00.00.01.418.44.82.00.00.00.026.6
1979-800.00.00.00.00.3T4.27.48.75.00.00.025.6
1980-810.00.00.00.08.01.10.68.20.20.00.00.018.1
1981-820.00.00.00.0T7.916.69.00.42.70.00.036.6
1982-830.00.00.00.0TT3.30.31.42.40.00.07.4
1983-840.00.00.00.0T6.52.39.95.20.00.00.023.9
1984-850.00.00.00.01.71.85.11.3T0.00.00.09.9
1985-860.00.00.00.0T5.71.06.10.2T0.00.013.0
1986-870.00.00.00.0TT23.60.6T0.00.00.024.2
1987-880.00.00.00.0T7.31.46.72.80.00.00.018.2
1988-890.00.00.00.02.95.90.13.911.00.00.00.023.8
1989-900.00.00.0TT9.10.26.98.4TTT24.6
1990-910.00.00.00.0T13.21.9T1.70.00.00.016.8
1991-920.00.00.0T3.90.43.82.33.10.00.00.013.5
1992-930.00.00.00.0T0.75.520.83.00.30.6T30.9
1993-940.00.00.0T1.61.15.01.00.21.40.00.010.3
1994-950.00.00.00.00.00.13.51.60.5T0.00.05.7
1995-960.00.00.00.00.97.913.42.81.0T0.00.026.0
1996-97T0.00.0T1.513.10.8T4.20.00.0
1997-98T0.00.00.02.64.15.70.55.9T0.20.019.0
1998-990.00.00.00.00.01.812.01.50.5T0.00.015.8
1999-000.00.00.00.00.00.35.0T4.8T0.00.010.1
2000-010.00.00.00.00.015.90.71.6T0.40.00.018.6
2001-0.00.00.0T0.2T
POR=64 YRS0.00.00.0T1.43.85.44.13.70.5TT18.9

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