Alton, IL vs Seattle, WA

Side-by-side comparison of monthly climate normals (NOAA 1991-2020).

Alton is about the same temperature as Seattle (55.7°F vs 53.8°F annual avg) and wetter than it (41.9 in vs 36.5 in per year). Alton has a Hot-summer humid continental climate; Seattle a Warm-summer Mediterranean climate.

Alton, IL

Annual avg
55.7°F
Annual precip
41.9 in
Warmest month
July (87.3°F)
Coldest month
January (21.7°F)
Annual swing
48°F
Pleasant months
1 / 12
Hot-summer humid continental Dfa USDA Zone 7b

Seattle, WA

Annual avg
53.8°F
Annual precip
36.5 in
Warmest month
August (77.4°F)
Coldest month
December (36.2°F)
Annual swing
25.8°F
Pleasant months
4 / 12
Warm-summer Mediterranean Csb USDA Zone 9a

Best months to visit each city

Alton

J
F
M
A
M
J
J
A
S
O
N
D

Seattle

J
F
M
A
M
J
J
A
S
O
N
D

Month-by-month comparison

Month Alton Seattle
High Low Precip High Low Precip
January 39.0°F 21.7°F 2.53 in 48.6°F 36.8°F 5.21 in
February 43.7°F 25.2°F 2.52 in 50.7°F 36.8°F 3.71 in
March 53.5°F 34.7°F 3.46 in 54.8°F 39.4°F 3.94 in
April 66.1°F 45.2°F 4.92 in 59.8°F 43.6°F 2.89 in
May 75.0°F 56.1°F 5.46 in 66.5°F 49.3°F 1.98 in
June 83.7°F 65.6°F 3.40 in 71.2°F 54.0°F 1.22 in
July 87.3°F 69.3°F 3.95 in 77.3°F 57.5°F 0.56 in
August 86.0°F 67.3°F 3.30 in 77.4°F 58.1°F 0.83 in
September 80.1°F 59.8°F 3.38 in 71.7°F 53.9°F 1.37 in
October 67.9°F 48.0°F 2.93 in 61.0°F 46.4°F 3.49 in
November 54.3°F 36.5°F 3.43 in 53.0°F 39.9°F 5.80 in
December 43.5°F 27.1°F 2.59 in 47.8°F 36.2°F 5.49 in
Alton overview
Full climate profile
 Seattle overview
Full climate profile