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United States of America

SEA-TAC, WASHINGTON


Home > North America > United States > Washington
Elevation: 450 feet     Latitude: 47 27N     Longitude: 122 18W

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MONTHLY - ALL WEATHER AVERAGES   [ Show Summary ]
[ °C ]   °F
TEMPERATURE 
Average Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F53.242.343.547.451.156.861.966.66761.652.945.940.7

Average High Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F6147.750.654.659.365.570.876.577.171.260.351.945.9

Average Low Temperature
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F45.436.936.540.142.848.152.956.656.85245.439.935.5

Highest Recorded Temperature
Years on Record: 68  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F1036470788593961039998897464

Lowest Recorded Temperature
Years on Record: 68  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F------1112928384344352866

Average Number of Days Above 100F/38C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days0.1------------------0.1---------------

Average Number of Days Above 90F/32C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days2.1---------------0.31.30.50.1---------

Average Number of Days Above 80F/26C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days26---------0.113.999.32.7---------

Average Number of Days Above 70F/21C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days93.5------0.42.16.914.125.427.116.11.30.1---

Average Number of Days Above 65F/18C
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days127------1513212929226------

Average Number of Days Above 60F/15C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days178.60.30.7511.724.728.230.93129.215.41.50.2

Average Number of Days Above 50F/10C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days29011.215.524.828.4313031313030.419.87

Average Number of Days Above 40F/4C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days356.828.127.730.83031303131303129.326.7

Average Number of Days Below 70F/21C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days364.931283130313030.93130313031

Average Number of Days Below 60F/15C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days353.53128313030.929.626.525.229.3313031

Average Number of Days Below 50F/10C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days240.730.72830.628.820.86.50.60.88.924.92931

Average Number of Days Below 40F/4C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days107.321.219.614.97.81------------5.313.823.8

Average Number of Days Below 32F/0C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days25.76.65.71.80.1---------------0.53.57.7

Average Number of Days Below 20F/-6C
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days1.50.3---------------------------0.21



PRECIPITATION 
Average Precipitation
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
in.40.15.74.343.12.11.60.90.91.73.86.55.4

Average Precipitable Water
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
in.0.60.50.40.50.50.60.80.90.90.80.60.50.5



PRECIPITATION - RAIN 
Average Number of Rainy Days
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days15418161714109569131819

Average Number of Days With Thunderstorms
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days8------1111111---1---

Most Rain Reported in a Month
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
in.55.112.99.18.46.54.83.82.44.65.97.810.711.8

Least Recorded Rainfall
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
in.23.70.60.30.60.30.10.1---------0.30.71.4



PRECIPITATION - SNOW 
Average Snowfall
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
in.11.851.61.40.1------------------1.22.5



HUMIDITY 
Average Relative Humidity
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%75.280.976.776.773.771.469.967.16973.880.582.580.9

Average Morning Relative Humidity
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%83838384838079798388888685

Average Evening Relative Humidity
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%62756963575453495156687679

Average Dew Point
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
F43333536394448525350453935



DEGREE DAYS 
Heating Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days45337046015474182591193424123377573753

Cooling Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days218------------525828421---------

Growing Degree Days
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days2194522670214356513525348114192



SKY CONDITIONS 
Average Length of Day
Years on Record: 30  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Hours12.89.610.912.514.215.816.616.114.71311.39.99.1

Average Number of Days With Fog
Years on Record: 48  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days164181513108881116191919

Average Number of Clear Days
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days583333451098432

Average Possibility of Sunshine
Years on Record: 27  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%47263949525556646561432822

Average Number of Cloudy Days
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days226242122201817111213202325

Average Number of Partly Cloudy Days
Years on Record: 49  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
Days8144679810109744

Average Total Sky Cover
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%6980.271.376.173.269.868.451.351.853.470.579.881

Average Opaque Sky Cover
Years on Record: 20  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
%64.175.966.371.267.564.262.948.147.24866.175.776.3



WIND 
Highest Reported Hourly Wind Speed
Years on Record: 44  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
mph66475144383236262936396652



SOLAR RADIATION 
Average Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m23.61.22.13.14.45.25.86.45.64.32.51.41

Average Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m21.70.71.11.72.12.52.62.62.21.91.30.80.6

Average Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m23.9233.84.54.855.75.64.93.42.21.7

Average Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m23.71.72.73.244.55.16.35.94.83.21.91.5

Maximum Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m23.61.22.13.14.45.25.86.45.64.32.51.41

Maximum Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m21.80.91.21.82.22.52.72.82.32.11.510.7

Maximum Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m24.72.73.44.95.36.15.86.66.25.94.432

Maximum Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m24.92.33.24.65.46.96.77.76.75.94.32.71.9

Minimum Daily Solar Radiation - Global
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m231.11.62.63.74.14.85.353.52.11.20.9

Minimum Daily Solar Radiation - Diffuse
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m21.60.70.91.62.12.42.62.52.21.71.10.70.6

Minimum Daily Solar Radiation - Reflected
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m23.21.62.233.83.84.14.74.93.92.71.71.5

Minimum Daily Solar Radiation - Direct
Years on Record: 22  Chart This
 ANNUAL  JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC 
kWh/m22.71.41.82.32.92.83.44.54.83.52.41.41.3




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