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
81.7
77
84
73
95
75
February
82.7
94
77
74
72
89
March
92.2
95
91
96
88
81
April
96.4
94
99
94
95
May
96.9
96
94
100
99
June
95.2
99
86
99
96
July
90.4
98
70
99
94
August
85.7
72
87
87
88
September
90.3
87
88
88
90
October
79.7
80
74
71
77
November
75.7
81
71
78
83
December
83.2
84
62
64
98
Average
89.3
89.8
88.3
83.3
89.4
89.9
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
-18.0
-20
-16
-19
-14
-26
February
-12.0
-9
-14
-13
-17
-13
March
-4.5
-3
-4
-3
-6
-6
April
6.0
0
5
6
6
May
16.9
17
15
16
19
June
21.8
21
23
23
20
July
23.3
25
23
24
21
August
19.2
21
20
18
21
September
13.4
12
14
12
14
October
2.4
0
1
1
2
November
-10.3
-6
-9
-16
-12
December
-14.3
-16
-15
-14
-12
Average
2.2
-11.1
3.3
4.1
2.9
2.7
Average highest temperature per day
The maximum temperature is typically observed some hours after noon.