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
79.1
82
59
64
88
94
February
81.7
84
62
71
91
88
March
88.6
87
89
78
85
89
April
94.0
77
95
95
96
May
95.6
99
94
97
92
June
95.6
100
92
99
92
July
96.9
100
98
97
95
August
94.5
95
91
94
97
September
89.2
89
86
85
95
October
84.6
75
81
87
86
November
76.7
65
76
84
89
December
74.9
70
60
89
75
Average
88.9
84.7
84.3
85.0
91.9
91.8
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
-16.9
-18
-12
-16
-12
-22
February
-9.7
-8
-8
-4
-14
-8
March
-3.9
-1
-2
-1
-6
-3
April
6.6
3
6
6
6
May
14.1
12
12
13
17
June
19.6
19
21
20
18
July
22.0
23
21
21
21
August
18.8
21
17
19
19
September
13.2
11
12
12
13
October
3.6
1
2
3
3
November
-8.1
-5
-8
-13
-11
December
-12.7
-12
-16
-14
-9
Average
2.8
-10.9
3.9
4.1
3.0
3.7
Average highest temperature per day
The maximum temperature is typically observed some hours after noon.