Percentage of observations where the VFR minimums for ceiling and visibility are met: visibility of 5 mi or more and a ceiling of 3,000 ft or more. Only observations between sunrise and sunset are taken into account.
Marginal VFR conditions (%)
Month
Average
2024
2023
2022
2021
2020
January
72.6
60
72
76
68
91
February
75.7
67
72
72
73
88
March
76.7
67
72
80
68
86
April
80.8
80
78
71
79
May
85.0
91
82
80
81
June
84.5
78
84
96
80
July
86.2
84
77
97
92
August
87.0
84
81
90
89
September
86.0
71
87
86
84
October
79.5
84
72
74
82
November
74.4
82
75
62
79
December
68.7
67
50
72
72
Average
79.9
64.8
78.7
77.5
77.6
83.7
Marginal VFR conditions or better during daylight period
Percentage of observations where the MVFR minimums for ceiling and visibility are met: visibility of 3⅛ mi or more and a ceiling of 1,000 ft or more. Only observations between sunrise and sunset are taken into account.
Maximum temperatures (°C)
Month
Average
2024
2023
2022
2021
2020
January
-17.9
-13
-15
-21
-11
-16
February
-16.6
-10
-18
-19
-11
-15
March
-7.0
-3
-6
-8
-7
-9
April
-1.7
3
0
3
-2
May
7.0
10
8
7
5
June
14.4
18
17
14
14
July
18.4
22
16
18
20
August
17.4
17
18
19
19
September
11.5
14
13
13
10
October
4.4
7
6
8
1
November
-6.7
-5
-5
-2
-4
December
-11.3
-8
-6
-12
-9
Average
0.0
-9.4
3.3
1.9
2.0
1.0
Average highest temperature per day
The maximum temperature is typically observed some hours after noon.