2001 Portland, Oregon (PDX)

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2001 PORTLAND, OREGON (PDX)

The Portland Weather Service Office is located 6 miles north–northeast of downtown Portland. Portland is situated about 65 miles inland from the Pacific Coast and midway between the northerly oriented low coast range on the west and the higher Cascade range on the east, each about 30 miles distant. The airport lies on the south bank of the Columbia River. The coast range provides limited shielding from the Pacific Ocean. The Cascade range provides a steep slope for orographic lift of moisture–laden westerly winds and consequent moderate rainfall, and also forms a barrier from continental air masses originating over the interior Columbia Basin. Airflow is usually northwesterly in Portland in spring and summer and southeasterly in fall and winter. The Portland Airport location is drier than most surrounding localities.

Portland has a very definite winter rainfall climate. Approximately 88 percent of the annual total occurs in the months of October through May, 9 percent in June and September, while only 3 percent comes in July and August. Precipitation is mostly rain, as on the average there are only five days each year with measurable snow. Snowfalls are seldom more than a couple of inches, and generally last only a few days.

The winter season is marked by relatively mild temperatures, cloudy skies and rain with southeasterly surface winds predominating. Summer produces pleasantly mild temperatures, northwesterly winds and very little precipitation. Fall and spring are transitional in nature. Fall and early winter are times with most frequent fog.

At all times, incursions of marine air are a frequent moderating influence. Outbreaks of continental high pressure from east of the Cascade Mountains produce strong easterly flow through the Columbia Gorge into the Portland area. In winter this brings the coldest weather with the extremes of low temperature registered in the cold air mass. Freezing rain and ice glaze are sometimes transitional effects. Temperatures below zero are very infrequent. In summer, hot, dry continental air brings the highest temperatures. Temperatures above 100 degrees are infrequent, but 90 degrees or higher are reached every year, but seldom persist for more than two or three days.

Destructive storms are infrequent in the Portland area. Surface winds seldom exceed gale force and rarely in the period of record have winds reached higher than 75 mph. Thunderstorms occur about once a month through the spring and summer months. Heavy downpours are infrequent but gentle rains occur almost daily during winter months.

Most rural areas around Portland are farmed for berries, green beans, and vegetables for fresh market and processing. The long growing season with mild temperatures and ample moisture favors local nursery and seed industries.

Based on the 1951–1980 period, the average first occurrence of 32 degrees Fahrenheit in the fall is November 7 and the average last occurrence in the spring is April 3.

NORMALS, MEANS, AND EXTREMES

PORTLAND, OR (PDX)

LATITUDE:    LONGITUDE:    ELEVATION (FT):    TIME ZONE:    WBAN: 24229

45 35′ 27″ N  122 36′ 01″ W  GRND:  220  BARO:  223  PACIFIC (UTC + 8)

ELEMENTPORJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECYEAR
TEMPERATURE FNORMAL DAILY MAXIMUM3045.451.056.060.667.174.079.980.374.664.052.645.662.6
MEAN DAILY MAXIMUM7144.750.155.761.367.673.179.679.574.564.052.646.362.4
HIGHEST DAILY MAXIMUM6163718090100100107107105927365107
YEAR OF OCCURRENCE198619881947199819831992196519811988198719751993AUG 1981
MEAN OF EXTREME MAXS.7156.860.668.777.785.790.595.594.690.278.663.657.776.7
NORMAL DAILY MINIMUM3033.736.138.641.347.052.956.556.952.044.939.534.844.5
MEAN DAILY MINIMUM7134.136.439.042.447.853.156.756.952.445.939.935.945.0
LOWEST DAILY MINIMUM61-2-31929293943443426136-3
YEAR OF OCCURRENCE195019501989195519541966195519801965197119851964FEB 1950
MEAN OF EXTREME MINS.7121.424.529.433.838.445.749.549.242.934.728.524.135.2
NORMAL DRY BULB3039.643.647.351.057.163.568.268.663.354.546.140.253.6
MEAN DRY BULB7139.443.247.451.957.863.268.268.263.454.946.241.153.7
MEAN WET BULB1738.840.144.047.852.256.256.357.154.050.644.235.948.1
MEAN DEW POINT1735.335.739.543.147.450.950.851.748.946.641.232.643.6
NORMAL NO. DAYS WITH:
MAXIMUM 90300.00.00.00.00.41.44.04.51.60.10.00.012.0
MAXIMUM 32301.70.10.00.00.00.00.00.00.00.00.21.43.4
MINIMUM 323012.47.74.21.10.10.00.00.00.00.64.610.441.1
MINIMUM 0300.00.00.00.00.00.00.00.00.00.00.00.00.0
H/CNORMAL HEATING DEG. DAYS307875995494202499128351023265677694522
NORMAL COOLING DEG. DAYS30000004612714751000371
RHNORMAL (PERCENT)3081787572696663656978828373
HOUR 04 LST3085858585848280828690878685
HOUR 10 LST3082807570666461646778828373
HOUR 16 LST3074665955524944444860737858
HOUR 22 LST3082807774726966687482838476
SPERCENT POSSIBLE SUNSHINE4628384852575669666244282348
W/OMEAN NO. DAYS WITH:
HEAVY FOG(VISBY 1/4 MI)594.33.72.31.10.10.10.10.22.66.75.74.731.6
THUNDERSTORMS610.10.10.50.91.40.90.81.00.70.40.30.17.2
CLOUDINESSMEAN:
SUNRISE-SUNSET (OKTAS)476.76.66.46.25.85.43.84.04.35.66.46.85.7
MIDNIGHT-MIDNIGHT (OKTAS)316.36.05.75.75.34.93.63.63.95.06.36.45.2
MEAN NO. DAYS WITH:
CLEAR472.92.93.33.55.06.212.611.410.35.42.82.168.4
PARTLY CLOUDY473.63.84.95.87.27.78.59.68.17.64.33.374.4
CLOUDY4724.421.522.820.718.916.19.910.111.618.022.925.5222.4
PRMEAN STATION PRESSURE(IN)2930.0929.9930.0030.0030.0030.0030.0030.0030.0030.0030.0030.1030.02
MEAN SEA-LEVEL PRES. (IN)1730.0930.0430.0630.0630.0330.0430.0530.0230.0230.0830.0730.1430.06
WINDSMEAN SPEED (MPH)479.99.48.37.57.27.37.67.16.56.68.69.68.0
PREVAIL. DIR (TENS OF DEGS)3112121232323233333212121232
MAXIMUM 2-MINUTE:
SPEED (MPH)643404337333424263137433843
DIR. (TENS OF DEGS)20102118242018320711201920
YEAR OF OCCURRENCE200020001999199620001997199619992000199919982001JAN 2000
MAXIMUM 5-SECOND:
SPEED (MPH)659515146404029334043515159
DIR. (TENS OF DEGS)19172009242018170812212219
YEAR OF OCCURRENCE200019961999199920001997199619972000199919981996JAN 2000
PRECIPITATIONNORMAL (IN)305.353.853.562.392.061.480.631.091.752.675.346.1336.30
MAXIMUM MONTHLY (IN)6112.8310.037.525.265.554.062.684.534.308.4111.5713.3513.35
YEAR OF OCCURRENCE195319961957199319981984198319681986199419421996DEC 1996
MINIMUM MONTHLY (IN)610.060.721.100.530.100.030.00TT0.190.771.380.00
YEAR OF OCCURRENCE198519931965195619921951196719701993198819761976JUL 1967
MAXIMUM IN 24 HOURS (IN)612.612.461.831.471.471.821.091.542.384.444.102.594.44
YEAR OF OCCURRENCE197419941943196219681958197819771982199419961977OCT 1994
NORMAL NO. DAYS WITH:
PRECIPITATION 0.013017.515.517.114.311.88.54.25.38.012.018.518.7151.4
PRECIPITATION 1.00301.10.40.20.20.10.10.00.10.20.20.81.14.5
SNOWFALLNORMAL (IN)301.80.90.1TT0.00.00.00.00.00.52.05.3
MAXIMUM MONTHLY (IN)5541.413.212.9T0.6T0.0TT0.28.215.741.4
YEAR OF OCCURRENCE19501949195119951953199519891949195019551968JAN 1950
MAXIMUM IN 24 HOURS (IN)5510.66.47.7T0.5T0.0TT0.27.48.010.6
YEAR OF OCCURRENCE19501993195119951953199519891949195019771964JAN 1950
MAXIMUM SNOW DEPTH (IN)4815145000000051115
YEAR OF OCCURRENCE19501950195119771964JAN 1950
NORMAL NO. DAYS WITH:
SNOWFALL 1.0300.60.30.*0.00.00.00.00.00.00.00.10.71.7
PRECIPITATION (inches) 2001 PORTLAND, OR (PDX)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19725.714.085.412.982.230.680.560.673.060.873.788.7938.82
19733.691.942.451.331.431.450.061.413.293.1411.559.9341.67
19748.514.615.651.761.740.802.010.070.212.146.736.0540.28
19758.434.753.451.881.351.130.432.10T4.764.106.6839.06
19765.144.922.932.342.290.780.663.290.731.480.771.3826.71
19771.072.493.501.044.300.830.393.263.332.285.568.9837.03
19784.853.281.493.963.171.691.362.052.070.363.832.5130.62
19792.556.532.512.472.410.640.251.181.754.853.387.2335.75
19808.514.013.112.582.192.500.190.391.561.186.479.7242.41
19811.473.862.331.792.253.230.240.151.864.124.628.3734.29
19826.315.982.383.560.461.660.941.663.984.443.518.1643.04
19836.237.786.801.871.301.952.682.290.391.958.655.3047.19
19842.013.933.193.203.414.06T0.091.463.859.742.5637.50
19850.061.793.081.071.522.340.550.482.762.753.892.1922.48
19864.655.312.601.912.190.231.200.104.301.996.264.3035.04
19876.932.454.911.941.630.141.030.350.300.271.968.0029.91
19884.951.173.134.572.532.340.690.101.760.197.922.3731.72
19893.302.846.732.082.870.780.911.071.481.733.183.0830.05
19907.953.432.522.312.371.940.320.950.344.653.682.4032.86
19912.563.654.644.053.342.310.070.700.021.516.364.3433.55
19924.314.121.873.820.100.600.670.491.122.874.554.9829.50
19933.060.724.395.264.361.692.410.37T1.591.505.0130.36
19943.564.921.841.910.561.670.070.131.138.415.914.8534.96
19955.563.193.823.491.652.621.230.811.313.1511.155.3543.33
19967.1510.033.245.124.880.440.730.253.055.399.5813.3563.21
19977.321.637.143.733.632.830.521.581.986.404.023.0343.81
19986.775.274.061.045.551.730.59T1.092.1611.026.7446.02
19996.638.734.031.561.971.730.510.750.102.446.813.6238.88
20005.664.503.211.822.701.190.150.121.673.252.463.4730.20
20011.471.293.112.850.911.790.950.740.703.126.896.6230.44
POR=61 YRS5.424.083.692.442.231.600.610.871.603.185.635.8437.19
AVERAGE TEMPERATURE (F) 2001 PORTLAND, OR (PDX)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
197239.243.849.848.060.264.070.971.761.253.048.237.454.0
197339.044.947.952.359.463.970.365.964.454.344.244.754.3
197438.043.047.251.355.764.467.168.967.355.248.144.154.2
197541.541.245.047.357.561.969.065.365.753.546.042.753.1
197642.242.144.450.356.660.467.265.564.254.747.039.552.8
197735.744.645.552.953.863.966.371.760.853.843.342.052.9
197840.144.749.150.554.765.168.467.660.954.739.135.352.5
197930.742.950.853.160.165.170.568.666.358.145.044.454.6
198035.142.546.353.857.360.768.966.463.856.048.544.053.6
198143.944.048.852.557.561.867.572.264.953.348.842.754.8
198239.743.648.549.057.666.067.568.663.254.944.441.753.7
198344.447.350.752.760.462.866.569.161.554.249.336.454.6
198442.245.951.150.456.462.269.169.463.752.946.738.354.0
198536.141.145.853.958.364.474.169.360.852.737.333.052.2
198642.543.751.350.257.666.365.372.361.557.047.740.654.7
198739.645.248.754.260.466.567.270.565.558.248.839.155.3
198839.044.747.252.256.462.468.468.064.058.347.542.054.2
198942.236.045.656.058.064.365.566.165.354.948.640.353.6
199043.441.949.454.556.763.671.270.967.053.948.434.754.6
199138.948.846.250.854.759.969.970.167.455.447.542.754.4
199244.548.152.355.463.167.470.269.862.355.946.339.356.2
199336.540.147.952.661.162.564.368.565.757.441.541.453.3
199444.540.950.254.260.762.971.170.267.654.142.742.355.1
199543.446.548.351.360.763.870.667.367.154.551.742.455.6
199640.741.647.753.555.363.272.070.461.854.045.541.653.9
199741.042.946.751.062.262.768.971.665.953.749.841.154.8
199843.046.148.852.856.363.471.071.066.954.348.940.555.3
199942.843.745.850.754.961.267.269.064.655.150.143.954.1
200039.843.745.654.057.665.367.867.863.955.242.840.453.7
200141.242.048.049.659.461.066.569.265.153.648.042.053.8
POR=61 YRS39.343.346.851.357.461.566.866.963.454.446.040.853.2

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 PORTLAND, OR (PDX)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-73106153363497848799560525378202894430
1973-7464759326618624832610545403282724424
1974-753216293015006407226606155232401274405
1975-762441483545656866986586324372581554556
1976-77154147319536783901564596358340684568
1977-784019131339644707764561485430317584495
1978-7929261343127729151058615434351162574865
1979-8082192145926319206475753292321254294
1980-811525642844856446505834943722291083953
1981-8223576355478687780596502472229714274
1982-83221099307614715635492435363184813957
1983-842721093254638807015464254302691154292
1984-859280377539820893664588327213624574
1985-8607124373826982691591417437265434756
1986-87370148242510750780550495321173514057
1987-88222542144797988015815443802721094256
1988-89331591208518705699805594263219774227
1989-90322744306486759664641476308251784072
1990-91105143364929338024465754203101564499
1991-9241325295517685627483387282108353461
1992-9359107274556789877692522366135944426
1993-94371757231698726630668451316143854059
1994-9516023330662696666514510405149954066
1995-9631520318392693747671530340294704093
1996-97168113340581717737612563413116794295
1997-987042341452734676523498376268723989
1998-99124323234757536775925874243121504341
1999-00381673298441648774612593323229624107
2000-011913752966617597336405174552011404509
2001-22555347504706
COOLING DEGREE DAYS (base 65 F) 2001 PORTLAND, OR (PDX)
YEARJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECANNUAL
19720000273920022144000531
1973000034651788145000403
19740000160102144102000409
1975000012391575775200342
19760000423896630400216
197700000429023310000375
1978000036914111218000343
19790000186518312465700462
198000010214175351200266
1981000341610923282000446
19820000410710312750000391
1983000048238013712000300
19840000103414014447600381
1985000011532911455000505
1986000040875223550000464
198700043710295177771200504
19880000103914711567800386
19890000962536660000250
1990000234520619383000532
1991000007164176102200451
199200015711417416431000541
1993000021242213280300282
199400001531210168109000533
1995000023631849291000453
1996000013624018125700490
19970000371613421075000472
19980001443020619796000547
1999000094111114968000378
2000000037811310750000351
2001000135287514464000347
SNOWFALL (inches) 2001 PORTLAND, OR (PDX)
YEARJULAUGSEPOCTNOVDECJANFEBMARAPRMAYJUNTOTAL
1972-730.00.00.00.00.06.10.4TTT0.00.06.5
1973-740.00.00.00.0T0.0TTT0.0T0.0T
1974-750.00.00.00.00.0TT0.1TTT0.00.1
1975-760.00.00.00.0TTTTTTT0.0T
1976-770.00.00.00.00.00.0T0.0T0.0T0.0T
1977-780.00.00.00.07.6T0.00.00.1TT0.07.7
1978-790.00.00.00.03.02.41.91.1TT0.00.08.4
1979-800.00.00.00.00.0T12.4TTT0.0T12.4
1980-810.00.00.00.0TT0.0TTTTTT
1981-820.00.00.00.00.02.02.1TTT0.00.04.1
1982-830.00.00.0TT0.00.00.0TTT0.0T
1983-840.00.00.00.00.02.30.1TT0.0T0.02.4
1984-850.00.00.0T0.02.8T4.8TT0.00.07.6
1985-860.00.00.00.03.41.6T5.8TTT0.010.8
1986-870.00.00.00.0T0.10.0TTTT0.00.1
1987-880.00.00.00.00.02.90.60.00.0TT0.03.5
1988-890.00.00.00.0TT0.90.32.0T0.00.03.2
1989-900.0T0.0T0.00.0T8.3T0.00.00.08.3
1990-910.00.00.00.00.01.30.60.0TT0.00.01.9
1991-920.00.00.00.0T0.00.00.00.0T0.00.0T
1992-930.00.00.00.0T4.62.96.60.0TT0.014.1
1993-940.00.00.00.0TT0.02.6TT0.0T2.6
1994-950.00.00.00.00.31.1T3.60.4T0.0T5.4
1995-960.00.00.00.00.0
1996-97
1997-98
1998-99
1999-00
2000-01
2001-
POR=55 YRS0.0TT0.00.41.43.11.10.4T0.0T6.4

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