2001 Philadelphia, Pennsylvania (PHL)

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2001 PHILADELPHIA, PENNSYLVANIA (PHL)

The Appalachian Mountains to the west and the Atlantic Ocean to the east have a moderating effect on climate. Periods of very high or very low temperatures seldom last for more than three or four days. Temperatures below zero or above 100 degrees are a rarity. On occasion, the area becomes engulfed with maritime air during the summer months, and high humidity adds to the discomfort of seasonably warm temperatures.

Precipitation is fairly evenly distributed throughout the year with maximum amounts during the late summer months. Much of the summer rainfall is from local thunderstorms and amounts vary in different areas of the city. This is due, in part, to the higher elevations to the west and north. Snowfall amounts are often considerably larger in the northern suburbs than in the central and southern parts of the city. In many cases, the precipitation will change from snow to rain within the city. Single storms of 10 inches or more occur about every five years.

The prevailing wind direction for the summer months is from the southwest, while northwesterly winds prevail during the winter. The annual prevailing direction is from the west–southwest. Destructive velocities are comparatively rare and occur mostly in gustiness during summer thunderstorms. High winds occurring in the winter months, as a rule, come with the advance of cold air after the passage of a deep low pressure system. Only rarely have hurricanes in the vicinity caused widespread damage, primarily because of flooding.

Flood stages in the Schuylkill River normally occur about twice a year. Flood stages seldom last over 12 hours and usually occur after excessive thunderstorms. Flooding rarely occurs on the Delaware River.

NORMALS, MEANS, AND EXTREMES

PHILADELPHIA, PA (PHL)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 13739

39 52′ 06″ N  75 13′ 52″ W  GRND:  59  BARO:  62  EASTERN (UTC + 5)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3037.941.051.662.673.181.786.184.677.666.355.143.463.4
MEAN DAILY MAXIMUM5439.642.551.263.373.382.286.584.877.566.755.243.963.9
HIGHEST DAILY MAXIMUM607474879497100104101100968173104
YEAR OF OCCURRENCE195019971945197619911994196620011953194119931998JUL 1966
MEAN OF EXTREME MAXS.5459.861.973.082.688.693.595.993.990.381.872.563.379.8
NORMAL DAILY MINIMUM3022.824.833.242.152.761.867.266.358.746.437.628.145.1
MEAN DAILY MINIMUM5424.526.533.442.952.962.267.866.558.947.337.828.945.8
LOWEST DAILY MINIMUM60-7-4719284451443525151-7
YEAR OF OCCURRENCE198419611984198219661984196619861963196919761983JAN 1984
MEAN OF EXTREME MINS.548.710.518.730.040.750.257.555.544.233.323.814.032.3
NORMAL DRY BULB3030.433.042.452.462.971.876.775.568.256.446.435.854.3
MEAN DRY BULB5432.134.542.353.063.072.277.175.768.257.046.636.454.8
MEAN WET BULB1830.332.238.247.056.865.469.868.662.352.342.934.150.0
MEAN DEW POINT1823.324.530.039.750.660.365.464.457.747.036.627.043.9
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.00.40.84.08.86.41.90.00.00.022.3
MAXIMUM 32309.45.70.70.00.00.00.00.00.00.00.14.220.1
MINIMUM 323026.222.314.02.6*0.00.00.00.01.58.521.296.3
MINIMUM 0300.50.10.00.00.00.00.00.00.00.00.00.00.6
H/CNORMAL HEATING DEG. DAYS301073896701378123500322835589054954
NORMAL COOLING DEG. DAYS3000005820936332612817001101
RHNORMAL (PERCENT)3066646260656870707271686867
HOUR 01 LST3070686869768081828281757275
HOUR 07 LST3073717270747779818383787476
HOUR 13 LST3059555249535454555654565955
HOUR 19 LST3065615754596163656969666763
SPERCENT POSSIBLE SUNSHINE5849535555566261625959524956
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)622.62.31.71.21.31.00.81.01.53.02.32.521.2
THUNDERSTORMS620.30.31.02.04.15.15.54.82.40.80.60.227.1
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)16.45.6
MIDNIGHT-MIDNIGHT (OKTAS)15.6
MEAN NO. DAYS WITH:
CLEAR13.02.08.08.011.0
PARTLY CLOUDY11.04.05.03.0
CLOUDY13.06.08.07.09.0
PRMEAN STATION PRESSURE(IN)2930.0530.0530.0029.9529.9529.9529.9730.0130.0530.0730.0630.0630.01
MEAN SEA-LEVEL PRES. (IN)1830.1030.0930.0429.9829.9829.9729.9930.0330.0630.1030.1130.1030.05
WINDSMEAN SPEED (MPH)6110.410.911.410.99.68.88.27.98.48.99.710.19.6
PREVAIL. DIR (TENS OF DEGS)3829302923232323232323232923
MAXIMUM 2-MINUTE:
SPEED (MPH)644434037405141413936404551
DIR. (TENS OF DEGS)28292731313033253235282730
YEAR OF OCCURRENCE199919961996200119971998199919971998199619962000JUN 1998
MAXIMUM 5-SECOND:
SPEED (MPH)657525251517146524946525371
DIR. (TENS OF DEGS)18312628293032243135272830
YEAR OF OCCURRENCE199619961996200019971998199919971996199619962000JUN 1998
PRECIPITATIONNORMAL (IN)303.212.793.463.623.753.744.283.803.422.623.343.3841.41
MAXIMUM MONTHLY (IN)598.866.447.018.127.417.8810.429.7013.075.999.068.4713.07
YEAR OF OCCURRENCE197819791980198319481973199419551999199519721996SEP 1999
MINIMUM MONTHLY (IN)590.450.750.680.520.470.110.640.490.440.090.320.250.09
YEAR OF OCCURRENCE195519911966198519641949195719641968196319761955OCT 1963
MAXIMUM IN 24 HOURS (IN)552.701.963.082.763.184.624.495.686.773.853.993.036.77
YEAR OF OCCURRENCE197919662000197019841973198919711999198019771992SEP 1999
NORMAL NO. DAYS WITH:
PRECIPITATION 0.013010.49.810.010.611.210.09.18.77.97.39.910.5115.4
PRECIPITATION 1.00300.80.61.00.90.91.01.41.21.00.70.90.811.2
SNOWFALLNORMAL (IN)307.87.53.30.5T0.00.00.00.00.10.63.423.2
MAXIMUM MONTHLY (IN)5823.427.613.44.3TT0.00.00.02.18.818.827.6
YEAR OF OCCURRENCE197819791958197119631993197919531966FEB 1979
MAXIMUM IN 24 HOURS (IN)5813.221.312.04.3TT0.00.00.02.18.714.621.3
YEAR OF OCCURRENCE196119831993197119631993197919531960FEB 1983
MAXIMUM SNOW DEPTH (IN)53122212300000081222
YEAR OF OCCURRENCE196119831993199719531966FEB 1983
NORMAL NO. DAYS WITH:
SNOWFALL 1.0302.31.81.00.20.00.00.00.00.00.*0.20.96.4
PRECIPITATION (inches) 2001 PHILADELPHIA, PA (PHL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19722.345.092.694.084.115.792.623.761.123.779.065.2049.63
19733.932.963.526.684.147.882.392.033.392.160.646.3446.06
19742.952.144.912.773.214.432.083.834.681.930.814.0437.78
19754.002.914.682.974.997.576.322.217.213.243.142.8952.13
19764.501.662.382.064.353.424.042.172.444.300.321.6333.27
19772.611.334.195.590.705.331.478.703.443.117.765.1949.42
19788.861.354.311.766.011.755.276.041.591.202.205.6145.95
19798.746.442.434.083.984.343.955.954.893.842.481.6752.79
19802.270.967.014.793.221.736.580.802.795.032.850.7738.80
19810.502.941.613.604.534.404.545.112.832.680.954.1437.83
19824.453.162.666.064.475.761.942.202.321.943.671.8040.43
19832.813.536.708.127.032.750.682.573.453.695.717.3754.41
19842.222.816.144.256.872.856.993.281.962.561.562.1743.66
19851.552.441.950.524.991.884.662.825.781.546.090.9835.20
19864.133.381.254.460.701.994.103.702.332.226.275.8940.42
19874.581.171.163.633.152.014.823.722.782.622.081.6833.40
19882.724.112.242.923.670.578.073.162.622.165.171.0038.41
19892.413.254.412.276.764.739.443.925.033.441.791.2148.66
19904.091.442.593.166.083.392.624.071.711.681.173.7935.79
19914.100.754.132.811.823.364.793.863.581.611.553.8636.22
19920.881.313.191.262.741.845.052.003.041.233.264.6130.41
19931.973.036.614.202.421.521.985.186.662.692.233.6942.18
19944.273.276.442.863.661.7410.424.541.640.943.032.1144.92
19953.102.411.671.962.670.622.921.153.555.993.342.1531.53
19964.392.124.274.483.254.738.174.294.954.303.038.4756.45
19972.802.483.912.582.321.492.384.561.591.833.493.0932.52
19984.243.253.932.703.874.911.791.261.861.841.180.8231.65
19994.892.954.023.313.701.161.225.3213.073.552.312.9948.49
20003.222.026.323.053.033.825.542.908.281.512.212.8244.72
20012.773.045.441.493.995.931.300.972.580.830.562.1131.01
POR= 130 YRS3.243.023.603.323.443.544.204.253.332.683.073.1240.81
AVERAGE TEMPERATURE (F) 2001 PHILADELPHIA, PA (PHL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197235.132.440.749.763.668.777.176.069.252.743.639.954.1
197334.433.647.253.460.374.677.978.870.759.248.038.656.4
197435.931.743.355.862.470.376.976.868.154.848.539.455.3
197537.335.841.248.766.672.276.677.166.661.252.736.956.1
197628.740.946.356.662.775.275.374.867.352.539.930.354.2
197720.033.648.857.265.868.677.876.269.954.346.432.654.3
197828.024.739.050.661.472.675.679.268.555.547.938.653.5
197932.523.047.052.366.469.176.275.568.554.950.138.254.5
198031.829.740.254.765.470.678.580.072.254.943.232.554.5
198125.337.940.054.762.672.076.974.966.853.145.634.653.7
198224.734.441.750.265.968.776.973.567.656.948.441.354.2
198334.134.043.751.062.172.077.977.169.056.646.733.254.8
198426.238.735.550.260.273.073.975.264.761.244.441.953.8
198527.335.344.655.564.568.875.474.169.159.351.333.354.9
198632.832.144.553.366.873.878.174.068.357.844.537.955.3
198731.932.545.753.163.974.679.575.468.852.548.039.255.4
198827.334.644.751.363.672.380.778.366.751.847.735.454.5
198936.534.842.352.462.474.776.375.669.758.344.925.554.5
199040.341.246.153.361.372.278.075.868.061.949.742.157.5
199135.240.046.155.570.875.779.079.069.558.947.339.658.1
199235.737.541.653.262.571.377.173.568.455.248.038.855.2
199338.231.939.854.266.474.481.478.969.758.049.038.456.7
199427.433.242.859.562.578.182.174.968.357.551.741.956.7
199538.231.547.354.564.374.381.579.970.461.443.031.656.5
199630.233.938.752.760.673.074.474.568.756.341.340.253.7
199732.540.044.151.459.571.177.573.967.157.344.438.554.8
199841.041.845.555.366.271.577.578.071.858.348.242.058.1
199935.038.042.453.564.072.981.277.469.956.150.939.956.8
200032.137.548.052.664.272.674.174.166.457.745.431.354.7
200132.537.441.154.964.775.275.479.968.459.152.943.757.1
POR= 128 YRS32.834.041.952.463.171.976.874.968.457.346.436.454.7

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 PHILADELPHIA, PA (PHL)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-73002237863577594087454735917614707
1973-740018196507810897926667292128114452
1974-7500463135007868528127324836644594
1975-7600451523728661120692572307119134258
1976-7702423877431069139087350525873365378
1977-78002432855899811391121797423161105559
1978-795041296507811999117055637838174818
1979-8047283244398231021101676330172174815
1980-810022320646999122275276830912945171
1981-820058364576936124385071444050255256
1982-83083127749773095186165342312824561
1983-8400702835409811196756911438181135369
1984-85009213861370911618246273068994568
1985-8600381874079759909146283457764567
1986-8702123255609838101790459135912914747
1987-8800203795047961162876624404105324902
1988-89003540851390887684070037113804789
1989-900043220594121975766258837512764591
1990-9121551714537019206945762964403913
1991-92004221552777890378972035612494463
1992-9301493105048048249207733144764552
1993-940034219479820115688168119313204595
1994-9500202313927108249325423188204051
1995-9600211596561029107289480937019175208
1996-970034265704761999695643401172424716
1997-98204527861281173864461928767134116
1998-9900142074987069207516913367734203
1999-0000222754157721012792519371107154300
2000-01007323058410399997687343207444825
2001-0048211358652
COOLING DEGREE DAYS (base 65 F) 2001 PHILADELPHIA, PA (PHL)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720030471433813441533001074
1973000163529440443519323001400
1974000245517937337214551201165
1975000012122436638098421201243
197600064583263263151157001211
19770010321041504023551753601237
19780000572443384471538001247
197900659014635733913716101097
198000008919442847024410001435
19810009622243733151191001103
198200038514237628011531501037
1983000114321740938019927001286
19840000392602833249030001026
1985000278113333029116619001047
1986000013927841330712940001306
198700071012954563321420001333
1988000170259495418937001343
198900116229835733219218101262
1990009292022641334115283101274
19910012123032744343718330001672
1992000105420538026815813001088
199300009529851743818111601546
199400034634015403131254001480
199500086628451946818953101588
19960009612573013051512101087
19970000923039728011349001078
1998002031142163974102233001386
19990000512465083941774001380
200000038925128628612312001050
2001000227231633046815837101404
SNOWFALL (inches) 2001 PHILADELPHIA, PA (PHL)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.0TTTTTTT0.00.0T
1973-740.00.00.00.0T4.64.112.1TT0.00.020.8
1974-750.00.00.00.0T0.83.96.62.3T0.00.013.6
1975-760.00.00.00.00.01.16.43.16.90.00.00.017.5
1976-770.00.00.00.0T2.815.70.2T0.00.00.018.7
1977-780.00.00.00.00.20.223.419.012.1T0.00.054.9
1978-790.00.00.00.02.5T10.127.6TT0.00.040.2
1979-800.00.00.02.1T4.96.10.47.4T0.00.020.9
1980-810.00.00.00.00.21.45.0T8.80.00.00.015.4
1981-820.00.00.00.0T2.814.03.51.14.00.00.025.4
1982-830.00.00.00.00.06.80.226.10.91.90.00.035.9
1983-840.00.00.00.00.8T10.5T10.3T0.00.021.6
1984-850.00.00.00.0T0.211.94.4TT0.00.016.5
1985-860.00.00.00.00.01.53.411.5TT0.00.016.4
1986-870.00.00.00.0T0.415.210.1TT0.00.025.7
1987-880.00.00.00.01.41.510.61.5T0.00.00.015.0
1988-890.00.00.00.00.00.46.02.42.40.00.00.011.2
1989-900.00.00.00.04.65.31.40.92.42.40.00.017.0
1990-910.00.00.00.00.06.46.51.00.70.00.00.014.6
1991-920.00.00.00.0TT1.21.02.5T0.00.04.7
1992-930.00.00.00.0TT1.010.912.4T0.0T24.3
1993-940.00.00.00.0T0.94.113.24.90.00.00.023.1
1994-950.00.00.00.0T0.0T9.8T0.00.00.09.8
1995-960.00.00.00.01.97.333.812.97.22.40.00.065.5
1996-970.00.00.00.0TT1.74.15.51.60.00.012.9
1997-980.00.00.00.0T0.20.5T0.10.00.0T0.8
1998-990.00.00.00.00.02.04.90.74.90.00.00.012.5
1999-000.00.00.00.00.0T13.75.70.01.6T0.021.0
2000-010.00.00.00.00.010.53.810.01.8T0.00.026.1
2001-0.00.00.00.00.00.0
POR= 58 YRS0.00.00.00.00.73.16.06.43.40.3TT19.9

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