Seattle, Washington Weather Recordsand Averages
Seattle-Tacoma's mild climate is influenced by the Cascade Mountainsand to a lesser extent by the Olympic Mountains. The city's climate ischaracterized by mild temperatures, a pronounced though not sharply definedrainy season and considerable cloudiness, particularly during the winter months.The Cascades are very effective in shielding the Seattle–Tacoma area from thecold, dry continental air during the winter and the hot, dry continental airduring the summer months.
The dry season is centered around July and early August with July being thedriest month of the year. The rainy season extends from October to March withDecember normally the wettest month but precipitation is rather evenlydistributed through the winter and early spring months, with more than 75percent of the yearly precipitation falling during the winter wet season. Mostof the rainfall in the Seattle area comes from storms common to the middlelatitudes.
The occurrence of snow in the Seattle–Tacoma area is extremely variable andusually melts before accumulating to measurable depths. There are winters onrecord with only a trace of snow but at the other extreme, over 21 inches hasfallen in a 24–hour period. Usually, winter storms do not produce snow unlessthe storm moves in such a way to bring cold air out of Canada directly or withonly a short trajectory over water.
Seattle-Tacoma's average first occurrence of 32 degrees Fahrenheit in thefall is November 11 and the average last occurrence in the spring is March 24.
Temperature + Precipitation
Monthly Averages | Daily Extremes | Monthly Extremes | Max. Temp. | Min. Temp. | ||||||||||||
Temperatures in F | Max. | Min. | Avg | High | Date of daily extreme high | Low | Date of daily extreme low | Highest Avg | Year | Lowest Avg | Year | # Days >= 90 F | # Days <= 32 F | # Days <= 32 F | # Days<= 0 F | |
January | 45.0 | 35.1 | 40.1 | 64 | 20/1981 | 0 | 31/1950 | 47.0 | 2010 | 24.9 | 1950 | 0.0 | 1.4 | 9.8 | 0.0 | |
February | 49.0 | 36.7 | 42.9 | 70 | 27/1968 | 1 | 01/1950 | 48.7 | 1977 | 35.6 | 1956 | 0.0 | 0.2 | 6.5 | 0.0 | |
March | 52.2 | 38.2 | 45.2 | 78 | 29/2004 | 11 | 04/1955 | 50.3 | 1992 | 39.1 | 1955 | 0.0 | 0.0 | 3.8 | 0.0 | |
April | 57.4 | 41.3 | 49.4 | 85 | 30/1976 | 29 | 21/1951 | 53.5 | 1977 | 44.5 | 1955 | 0.0 | 0.0 | 0.4 | 0.0 | |
May | 64.2 | 46.5 | 55.3 | 93 | 21/1963 | 28 | 01/1954 | 60.4 | 1958 | 50.6 | 1962 | 0.1 | 0.0 | 0.0 | 0.0 | |
June | 69.4 | 51.4 | 60.4 | 96 | 09/1955 | 38 | 12/1952 | 64.9 | 1992 | 55.5 | 1953 | 0.5 | 0.0 | 0.0 | 0.0 | |
July | 75.3 | 54.8 | 65.0 | 103 | 29/2009 | 43 | 04/1949 | 69.5 | 2009 | 60.0 | 1955 | 1.3 | 0.0 | 0.0 | 0.0 | |
August | 74.8 | 55.0 | 64.9 | 99 | 09/1960 | 44 | 04/1950 | 71.1 | 1967 | 60.6 | 1954 | 0.8 | 0.0 | 0.0 | 0.0 | |
September | 69.4 | 51.5 | 60.4 | 98 | 02/1988 | 35 | 27/1972 | 65.7 | 1967 | 55.3 | 1972 | 0.2 | 0.0 | 0.0 | 0.0 | |
October | 59.3 | 45.4 | 52.3 | 89 | 01/1987 | 28 | 19/1949 | 56.4 | 1965 | 48.6 | 1949 | 0.0 | 0.0 | 0.4 | 0.0 | |
November | 50.5 | 39.6 | 45.1 | 74 | 04/1949 | 6 | 15/1955 | 49.4 | 1965 | 35.8 | 1985 | 0.0 | 0.2 | 4.0 | 0.0 | |
December | 45.4 | 35.9 | 40.6 | 64 | 10/1993 | 6 | 30/1968 | 45.2 | 1969 | 35.2 | 1990 | 0.0 | 0.9 | 8.5 | 0.0 | |
Annual | 59.3 | 44.3 | 51.8 | 103 | 2009/07/29 | 0 | 1950/01/31 | 54.4 | 1995 | 47.9 | 1955 | 2.8 | 2.7 | 33.3 | 0.0 | |
Winter | 46.5 | 35.9 | 41.2 | 70 | 1968/02/27 | 0 | 1950/01/31 | 45.0 | 1992 | 34.4 | 1950 | 0.0 | 2.5 | 24.7 | 0.0 | |
Spring | 57.9 | 42.0 | 50.0 | 93 | 1963/05/21 | 11 | 1955/03/04 | 54.4 | 1992 | 44.8 | 1955 | 0.1 | 0.0 | 4.3 | 0.0 | |
Summer | 73.2 | 53.7 | 63.4 | 103 | 2009/07/29 | 38 | 1952/06/12 | 66.7 | 1967 | 59.0 | 1954 | 2.6 | 0.0 | 0.0 | 0.0 | |
Fall | 59.7 | 45.5 | 52.6 | 98 | 1988/09/02 | 6 | 1955/11/15 | 55.9 | 1967 | 48.4 | 1985 | 0.2 | 0.2 | 4.3 | 0.0 |
Total Snowfall | ||||||||||||||
Avg. | High | Year | Low | Year | 1 Day Max. | >= 0.01 in. | >= 0.10 in. | >= 0.50 in. | >= 1.00 in. | Mean | High | Year | ||
in. | in. | - | in. | - | in. | dd/yyyy or yyyymmdd | # Days | # Days | # Days | # Days | in. | in. | - | |
January | 5.77 | 12.92 | 1953 | 0.58 | 1985 | 2.98 | 18/1986 | 19 | 13 | 4 | 1 | 5.0 | 57.2 | 1950 |
February | 3.92 | 9.11 | 1961 | 0.35 | 1993 | 3.06 | 08/1996 | 15 | 10 | 2 | 0 | 1.7 | 13.1 | 1949 |
March | 3.73 | 8.40 | 1950 | 0.57 | 1965 | 2.70 | 05/1972 | 17 | 11 | 2 | 0 | 1.3 | 18.2 | 1951 |
April | 2.54 | 6.53 | 1991 | 0.33 | 1956 | 2.64 | 04/1991 | 14 | 7 | 1 | 0 | 0.1 | 2.3 | 1972 |
May | 1.74 | 3.70 | 1977 | 0.12 | 1992 | 1.83 | 29/1969 | 11 | 5 | 1 | 0 | - | - | - |
June | 1.45 | 3.82 | 1964 | 0.13 | 1951 | 1.75 | 01/1968 | 9 | 4 | 1 | 0 | - | - | - |
July | 0.74 | 2.39 | 1983 | 0.00 | 1958 | 0.85 | 13/1981 | 5 | 2 | 0 | 0 | - | - | - |
August | 1.10 | 4.59 | 1975 | 0.01 | 1974 | 1.63 | 18/1975 | 6 | 3 | 1 | 0 | - | - | - |
September | 1.77 | 5.95 | 1978 | 0.00 | 1975 | 1.65 | 30/1953 | 9 | 5 | 1 | 0 | - | - | - |
October | 3.48 | 8.96 | 2003 | 0.31 | 1987 | 5.02 | 20/2003 | 13 | 8 | 2 | 0 | 0.0 | 2.0 | 1971 |
November | 6.15 | 15.63 | 2006 | 0.74 | 1976 | 3.41 | 20/1959 | 18 | 13 | 4 | 1 | 0.9 | 17.5 | 1985 |
December | 5.81 | 11.85 | 1979 | 1.37 | 1978 | 3.77 | 03/2007 | 19 | 13 | 4 | 1 | 2.8 | 22.1 | 1968 |
Annual | 38.19 | 55.14 | 1950 | 23.78 | 1952 | 5.02 | 2003/10/20 | 155 | 94 | 22 | 5 | 11.8 | 60.6 | 1950 |
Winter | 15.50 | 22.77 | 1999 | 5.21 | 1977 | 3.77 | 2007/12/03 | 53 | 35 | 10 | 2 | 9.4 | 67.5 | 1969 |
Spring | 8.00 | 14.34 | 1997 | 3.24 | 1979 | 2.70 | 1972/03/05 | 42 | 23 | 3 | 0 | 1.4 | 18.2 | 1951 |
Summer | 3.29 | 8.43 | 1968 | 0.84 | 1987 | 1.75 | 1968/06/01 | 20 | 9 | 2 | 0 | - | - | - |
Fall | 11.40 | 18.61 | 2006 | 2.72 | 1952 | 5.02 | 2003/10/20 | 40 | 26 | 7 | 2 | 0.9 | 17.5 | 1985 |
Washington averages and extremes in precipitation and temperature and Top 10 U.S climate extremes.
Winter = Dec, Jan, and Feb | Spring = Mar, Apr, and May | |
Summer = Jun, Jul, and Aug. | Fall = Sep, Oct, and Nov |
Data period is 1948 - 2010, Seattle-Tacoma Airport. Source: Western Regional Climate Center