SEATTLE, WASHINGTON, SEATTLE - TACOMA AIRPORT
NORMALS, MEANS, AND EXTREMES

LATITUDE: 47 Deg. 27 Min. N LONGITUDE: 122 Deg. 18 Min. W ELEVATION: FT. GRND 400 BARO 451 TIME ZONE: PACIFIC WBAN: 24233

(a)
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
YEAR
TEMPERATURE (Deg. F)
Normals
-Daily Maximum
-Daily Minimum
-Monthly
Extremes
-Record Highest
-Year
-Record Lowest
-Year






51

51



45.0
35.2
40.1

64
1981
0
1950


49.5
37.4
43.5

70
1968
1
1950


52.7
38.5
45.6

75
1987
11
1955


57.2
41.2
49.2

85
1976
29
1975


63.9
46.3
55.1

93
1963
28
1954


69.9
51.9
60.9

96
1995
38
1952


75.2
55.2
65.2

100
1994
43
1954


75.2
55.7
65.5

99
1981
44
1955


69.3
51.9
60.6

98
1988
35
1972


59.7
45.8
52.8

89
1987
28
1949


50.5
40.1
45.3

74
1949
6
1955


45.1
35.8
40.5

64
1993
6
1968


59.4
44.6
52.0

100
JUL 1994
0
JAN 1950
NORMAL DEGREE DAYS
Heating (base 65 Deg. F)
Cooling (base 65 Deg. F)




772
0

602
0

601
0

474
0

307
0

144
21

58
64

65
81

156
24

378
0

591
0

760
0

4908
190
% OF POSSIBLE SUNSHINE
29
27
39
50
52
56
56
64
65
62
43
28
23
47
MEAN SKY COVER(tenths)
Sunrise - Sunset
MEAN NUMBER OF DAYS:
Sunrise to Sunset
-Clear
-Partly Cloudy
-Cloudy
Precipitation
.01 inches or more
Snow, Ice Pellets, Hail
1.0 inches or more
Thunderstorms
Heavy Fog Visibility
1/4 mile or less
Temperature Deg. F
-Maximum
90 Deg. F and above
32 Deg. F and below
-Minimum
32 Deg. F and below
0 Deg. F and below

51


51
51
51

51

51
51

51


36
36

36
36

8.4


2.8
3.9
24.2

18.3

1.5
0.2

5.2


0.0
1.0

9.6
0.0

8.1


2.9
4.2
21.2

15.5

0.5
0.3

3.5


0.0
0.2

5.4
0.0

7.9


3.4
5.8
21.9

16.8

0.5
0.6

2.4


0.0
0.0

2.8
0.0

7.8


2.7
7.3
19.9

14.0

0.*
1.0

1.1


0.0
0.0

0.2
0.0

7.1


4.5
8.8
17.6

10.4

0.0
0.9

0.7


0.2
0.0

0.0
0.0

7.0


5.1
7.8
17.0

9.0

0.0
0.7

0.7


0.4
0.0

0.0
0.0

5.3


10.4
9.7
10.7

5.1

0.0
0.7

1.5


1.2
0.0

0.0
0.0

5.7


9.1
9.9
12.1

6.1

0.0
0.7

2.5


1.2
0.0

0.0
0.0

6.0


8.2
8.6
13.2

8.7

0.0
0.7

5.1


0.3
0.0

0.0
0.0

7.5


4.0
7.4
19.5

13.0

0.*
0.4

7.2


0.0
0.0

0.2
0.0

8.4


2.5
4.2
23.3

18.0

0.3
0.7

5.4


0.0
0.2

3.6
0.0

8.6


2.3
3.9
24.9

19.1

0.9
0.3

6.1


0.0
1.1

8.9
0.0

7.3


57.8
81.6
225.5

154.2

3.7
7.2

41.3


3.3
2.4

30.8
0.0
AV. STATION PRES. (mb)
23
1001.1
1000.0
999.0
1000.7
1000.6
1000.9
1001.5
1000.5
1000.7
1001.5
1000.2
1001.3
1000.7
RELATIVE HUMIDITY (%)
Hour 04
Hour 10 (Local Time)
Hour 16
Hour 22

36
36
36
36

81
79
74
78

81
77
67
76

83
74
61
76

84
72
58
75

83
68
54
72

82
66
53
70

82
65
49
68

84
68
50
71

86
73
56
75

87
79
67
81

84
80
75
81

83
81
77
80

83
74
62
75
PRECIPITATION (in.)
Water Equivalent
-Normal
-Maximum Monthly
-Year
-Minimum Monthly
-Year
-Maximum in 24 hrs
-Year
Snow, Ice Pellets, Hail
-Maximum Monthly
-Year
-Maximum in 24 hrs
-Year



51

51

51


51

51



5.38
12.92
1953
0.58
1985
3.22
1986

57.2
1950
21.4
1950


3.99
9.11
1961
0.35
1993
3.41
1951

13.1
1949
9.8
1990


3.54
8.40
1950
0.57
1965
2.86
1972

18.2
1951
7.4
1989


2.33
6.53
1991
0.33
1956
3.32
1991

2.3
1972
2.3
1972


1.70
4.76
1948
0.12
1992
1.83
1969

T
1993
T
1993


1.50
3.90
1946
0.13
1951
2.08
1985

0.0

0.0



0.76
2.39
1983
T
1960
0.85
1981

T
1980
T
1980


1.14
4.59
1975
0.01
1974
1.75
1968

0.0

0.0



1.88
5.95
1978
T
1991
2.23
1978

T
1972
T
1972


3.23
8.95
1947
0.31
1987
3.74
1981

2.0
1971
2.0
1971


5.83
10.71
1990
0.74
1976
3.58
1990

17.5
1985
9.4
1946


5.91
11.85
1979
1.37
1978
2.61
1979

22.1
1968
13.0
1968


37.19
12.92
JAN 1953
T
SEP 1991
3.74
OCT 1981

57.2
JAN 1950
21.4
JAN 1950
WIND
Mean Speed (mph)
Prevailing Direction
through 1964
Fastest Mile
-Direction(!!)
-Speed(mph)
-Year
Peak Gust
-Direction(!!)
-Speed(mph)
-Date

47



27
27


12
12


9.6

SSW

S
47
1993

S
64
1993

9.5

SW

S
51
1981

S
46
1988

9.6

SSW

SW
44
1984

SW
46
1995

9.5

SW

SW
38
1972

SW
44
1990

8.9

SW

SW
32
1968

W
39
1993

8.7

SW

SW
29
1974

S
33
1994

8.3

SW

SW
26
1981

SW
29
1994

8.0

SW

SW
29
1977

S
38
1991

8.1

N

S
35
1990

S
39
1990

5.5

S

SW
38
1982

S
45
1990

9.3

S

S
66
1981

S
52
1991

9.6

SSW

S
49
1982

S
60
1995

9.0

SW

S
66
NOV 1981

S
64
JAN 1993
(a) - Length of Record in Years, although individual months may be missing.
0.* or * - The value is between 0.0 and 0.05.
Normals - Based on the 1961 - 1990 record period.
Extremes - Dates are the most recent occurrence.
Wind Dir.- Numerals show tens of degrees clockwise from true north. "00" indicates calm.
Resultant Directions are given to whole degrees.