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Clatsop County Climate

Average Temperature
January 41.9 degrees   July 60.1 degrees
Average Annual Precipitation – 66.4”

Clatsop County’s coastal zone is characterized with temperate weather. Fall, Winter and Spring can be quite wet, with an annual range of 65-90 inches of precipitation. Winter snowfall is minimal, and days of freezing temperatures are few. Spring brings light rain and fog. Summers are beautiful with rich sunsets and evening cools with a daily temperature range of 50-80 degrees. July, August and September are historically the warmest and driest of the season.

Table 1. Precipitation, Monthly and Annual Averages (1971-2000)
Name
Number
Jan
Feb.
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Annual
Astoria Airport
328
9.62
7.87
7.37
4.93
3.28
2.57
1.16
1.21
2.61
5.61
10.5
10.4
67.13
Seaside
7641
10.27
9.57
8.44
5.74
3.96
3
1.63
1.34
3
6.07
11.38
11.34
75.74

Table 2. Average number of Days with Selected Precipitation Amounts
Astoria WSO Airport, 1971-2000
Threshold
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
.01"or more
20.8
18.9
21
17.8
16
13.1
8.3
7.2
9.4
14.8
20.9
21.2
189.7
.10"or more
16.2
14.1
15.3
11.8
8.6
6.4
2.9
2.9
5.6
10.1
16.8
16.2
127.6
.50"or more
7.5
5.8
5.3
3
1.8
1.5
0.6
0.7
1.7
3.8
7.4
7.2
46.4
1.00"or more
2.4
1.7
1.5
0.5
0.3
0.3
0.2
0.2
0.5
1.4
2.6
3.2
14.9

Table 3. Monthly and Annual Average Temperatures (deg F)
Astoria WSO Airport (1862), 1971-2000
Parameter
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Mean max
48.1
50.8
53.3
56.1
60.0
63.6
67.2
68.3
67.5
61.0
53.1
48.4
58.1
Mean min
36.7
37.6
38.6
40.8
45.4
49.8
52.9
53.2
49.5
44.1
40.1
37.1
43.8
Mean temp
42.4
44.2
46.0
48.5
52.7
56.7
60.1
60.8
58.5
52.6
46.6
42.8
51.0
Extreme max
67
72
73
83
87
92
93
96
95
85
71
64
96
Extreme min
11
9
22
30
31
37
39
39
33
26
19
6
6

Table 4. Snowfall, Monthly and Annual Averages (1971-2000)
Name
Number
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Astoria WSO Airport
328
1.2
0.4
0.2
0.1
0
0
0
0
0
0
0.3
0.6
2.5
Seaside
7641
0.4
0
0
0
0
0
0
0
0
0
0
0
0.6

Table 5. Median Spring and Fall Frost Dates, Astoria WSO Airport, 1971-2000
Percentile
Last Date in Spring of Low Temperatures (deg F)
First Date in Fall of Low Temperatures (deg F)
24
28
32
36
24
28
32
36
10
1-Jan
28-Jan
8-Mar
10-Apr
21-Nov
11-Nov
16-Oct
29-Sep
20
1-Jan
31-Jan
19-Mar
21-Apr
1-Dec
17-Nov
26-Oct
2-Oct
50
29-Jan
12-Feb
9-Apr
5-May
1-Dec
1-Dec
7-Nov
13-Oct
80
8-Feb
6-Mar
25-Apr
12-May
1-Dec
18-Dec
25-Nov
21-Oct
90
15-Feb
15-Mar
29-Apr
15-May
19-Dec
18-Dec
1-Dec
26-Oct

Table 6. Average Growing Season, Astoria WSO Airport, 1971-2000
Percentile
Length of Time (Days) Between Occurrence of Temperatures
24
28
32
36
10
282
245
180
143
20
293
258
199
146
50
307
290
217
167
80
334
313
244
183
90
337
321
253
194

Prepared by George Taylor State Climatologist