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Volume of Seattle's Annual Precipitation

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Bibliographic Entry Result
(w/surrounding text)
"Seattle (Washington)" The New Book of Knowledge. Scholastic Library Publishing, 2006. "The city itself covers an area of 92 square miles (238 square kilometers). 236 million m3
"Annual precipitation averages 39 inches (990 millimeters), with the heaviest rains falling from October through March."
Seattle's Convention and Visitor's Bureau - Seattle Fact Sheet. Original Source: Official Readings of the Western Regional Climate Center, 1931-2000.
City, State Annual Precipitation
Seattle, WA 37.19 in.
(945 mm)
225 million m3
Monthly Averages for Seattle, WA [pdf]. The Weather Channel Interactive, Inc., 1995-2006. [see table] 224 million m3
Climatography of the United States, No. 20, 1971-2000 [pdf]. US Department of Commerce, NOAA, National Environmental Satellite, Data, and Information Service, 1971-2000.
Precipitation Totals
  Mean Median
Annual 37.07 in. (942 mm) 35.51 in. (902 mm)
224 million m3
About Seattle. City of Seattle, Department of Information Technology, 1995-2000.
Annual Precipitation
City/State Precipitation
Seattle, WA 38.6 in. (980 mm)
233 million m3
Monthly Averages
for Seattle, WA
Month Avg. Precip (in)
Jan 5.13
Feb 4.18
Mar 3.75
Apr 2.59
May 1.78
June 1.49
July 0.79
Aug 1.02
Sep 1.63
Oct 3.19
Nov 5.90
Dec 5.62
Total 37.07 (942 mm)

The next time someone asks you which city gets the most rainfall, you should think twice before you say Seattle. Seattle, Washington has always been known for its amount of precipitation but although common knowledge says that it is one of the rainiest cities, if you look at the numbers it becomes clear that there are many cities that have greater rainfall than Seattle. This is mostly because while it rains very often in Seattle, it usually rains at a steady but not heavy pace. Compared to other cities, the likelihood of it raining is greater but the rain in other cities is usually heavier, causing them to have larger averages.

The annual precipitation recorded in Seattle ranges from 942 mm (37.07 inches) to 990 mm (39 inches). In order to get the volume of Seattle's annual precipitation, m3, we have to multiply the area of the city in square meters by the average amount of rainfall in meters. According to The New Book of Knowledge, the area covered by the city of Seattle is 238 square kilometers, or 238,000,000 square meters. Doing the multiplication gives us a range of values from 224 million cubic meters to 236 million cubic meters.

These numbers are far less than those of a city like New York, where you don't expect there to be a very large total annual rainfall. If we say the average volume of precipitation in Seattle is 230 million cubic meters, this is only about 25% of New York's average of 914 million cubic meters (Volume of New York City's Annual Precipitation). So next time you plan on going to Seattle, bring your umbrella but you don't have to worry about those huge puddles.

Gina Castellano -- 2006