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
90.8
84
93
96
91
91
February
86.1
92
88
92
76
92
March
86.3
82
69
92
96
88
April
89.8
90
90
89
92
May
90.3
94
100
89
95
June
98.1
99
50
99
95
July
99.8
100
100
100
100
August
97.8
95
97
100
September
95.8
90
98
100
96
October
88.3
82
88
95
81
November
90.4
97
85
99
94
December
88.7
96
85
85
83
Average
90.6
85.7
91.2
90.7
93.4
93.0
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
3.1
1
4
5
5
1
February
-1.5
4
3
2
-7
4
March
5.6
5
1
8
10
6
April
10.9
12
9
12
10
May
17.2
21
17
17
17
June
23.5
23
18
27
23
July
29.4
30
31
31
28
August
28.3
30
27
30
September
23.3
24
25
25
23
October
12.6
13
16
17
8
November
7.2
10
3
12
9
December
3.4
9
-4
0
5
Average
10.0
3.2
14.8
8.6
14.6
13.8
Average highest temperature per day
The maximum temperature is typically observed some hours after noon.