National Weather Service United States Department of Commerce

Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

KMAF Aviation Climatology

The following values are percent of occurrence of different flying weather conditions.

The data was derived from 31 years of data (1973-2004).

Skip marginal visual flight rule occurrence table.

Ceiling between 1000-3000 feet and/or Visibility between 3-5 miles (MVFR)
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 7 % 6 % 6 % 4 % 4 % 1 % 1 % 2 % 4 % 5 % 5 % 5 % 4.2%
4 am 6 % 6 % 7 % 5 % 5 % 2 % 1 % 2 % 4 % 6 % 7 % 6 % 4.8%
7 am 6 % 7 % 10 % 7 % 9 % 3 % 2 % 1 % 5 % 8 % 8 % 7 % 6.1%
10 am 7 % 8 % 10 % 11% 12% 9 % 4 % 3 % 9 % 9 % 8 % 8 % 8.2%
1 pm 8 % 8 % 12 % 12% 16% 13% 8 % 7 % 14% 11% 10% 8 % 6.6%
4 pm 8 % 8 % 10 % 10% 12% 10% 7 % 7 % 12% 12% 9 % 6 % 8.7%
7 pm 9 % 9 % 8 % 7 % 7 % 5 % 4 % 3 % 9 % 9 % 8 % 8 % 7.2%
10 pm 8 % 8 % 7 % 4 % 5 % 2 % 2 % 2 % 5 % 5 % 7 % 7 % 5.2%

Skip instrument flight rule occurrence table.

Ceiling greater than or = 500 feet to less than 1000 feet and/or Visibility greater than or = to 1mile to less than 3 miles (IFR)
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 3 % 3 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 2 % 3 % 3 % 1.7%
4 am 3 % 4 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 3 % 3 % 4 % 1.9%
7 am 4 % 5 % 3 % 1 % 1 % 1 % 1 % 1 % 3 % 4 % 5 % 4 % 2.8%
10 am 4 % 7 % 4 % 4 % 3 % 1 % 2 % 2 % 4 % 6 % 5 % 4 % 3.8%
1 pm 6 % 7 % 4 % 6 % 5 % 2 % 2 % 2 % 5 % 7 % 6 % 3 % 4.6%
4 pm 7 % 6 % 4 % 3 % 2 % 1 % 1 % 1 % 5 % 6 % 5 % 5 % 3.8%
7 pm 5 % 6 % 3 % 1 % 1 % 0 % 0 % 0 % 3 % 3 % 4 % 4 % 2.5%
10 pm 4 % 3 % 2 % 2 % 1 % 0 % 1 % 0 % 2 % 2 % 2 % 4 % 1.9%

Skip low instrument flight rule occurrence table.

Ceiling greater than or = to 200 feet to less than 500 feet and/or Visibility greater than or = to 1/2 mile to less than 1 mile (LIFR)
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 2 % 2 % 0.9%
4 am 4 % 2 % 1 % 1 % 0 % 0 % 0 % 0 % 1 % 1 % 2 % 2 % 1.2%
7 am 4 % 3 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 2 % 3 % 2 % 1.7%
10 am 5 % 4 % 2 % 1 % 1 % 0 % 0 % 0 % 3 % 3 % 5 % 4 % 2.3%
1 pm 6 % 5 % 3 % 2 % 1 % 1 % 1 % 1 % 4 % 4 % 6 % 4 % 3.2%
4 pm 6 % 5 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 2 % 4 % 4 % 2.3%
7 pm 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 1 % 1 % 2 % 2 % 1.1%
10 pm 3 % 2 % 0 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 2 % 1 % 0.8%

Skip very low instrument flight rule occurrence table.

Ceiling less than 200 feet and/or Visibility less than 1/2 mile (VLIFR)
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 1 % 1 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 1 % 0.4%
4 am 3 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 am 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 3 % 1.1%
10 am 6 % 4 % 1 % 1 % 0 % 0 % 0 % 0 % 0 % 2 % 3 % 3 % 1.7%
1 pm 5 % 6 % 2 % 1 % 1 % 0 % 0 % 0 % 1 % 3 % 3 % 4 % 2.2%
4 pm 3 % 3 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 pm 1 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0.3%
10 pm 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0 % 0.2%

Skip marginal visual flight ruleand below occurrence table.

Ceiling less than or = to 3000 feet and/or Visibility less than or = to 5 miles
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 15% 12% 10% 5 % 5 % 0 % 0 % 0 % 0 % 0 % 1 % 1 % 0.4%
4 am 16% 14% 11% 0 % 6 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 am 18% 17% 16% 0 % 11% 0 % 0 % 0 % 0 % 1 % 2 % 3 % 1.1%
10 am 22% 23% 17% 1 % 16% 0 % 0 % 0 % 0 % 2 % 3 % 3 % 1.7%
1 pm 25% 26% 21% 1 % 1 % 0 % 0 % 0 % 1 % 3 % 3 % 4 % 2.2%
4 pm 24% 22% 16% 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 pm 19% 18% 12% 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0.3%
10 pm 16% 13% 9 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0 % 0.2%

Skip instrument flight rules and below occurrence table.

Ceiling less than 1000 feet and/or Visibility less than 3 miles
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 8% 12% 4% 1 % 1 % 0 % 0 % 0 % 2 % 2 % 6 % 6 % 3.5%
4 am 10% 8% 4% 2 % 1 % 0 % 0 % 0 % 3 % 4 % 6 % 8 % 3.8%
7 am 12% 10% 6% 2 % 2 % 1 % 1 % 1 % 5 % 7 % 10% 9 % 5.5%
10 am 15% 15% 7% 6 % 4 % 1 % 2 % 2 % 7 % 11% 13% 11% 7.8%
1 pm 17% 18% 9% 9 % 7 % 3 % 3 % 3 % 10% 14% 15% 11% 9.9%
4 pm 16% 14% 6% 4 % 3 % 1 % 1 % 1 % 7 % 8 % 10% 11% 6.8%
7 pm 10% 9% 4% 1 % 1 % 0 % 0 % 0 % 4 % 4 % 6% 7 % 3.8%
10 pm 8% 5% 2 % 3 % 1 % 0 % 1 % 0 % 2 % 2 % 5% 5 % 2.8%

Skip low instrument flight rules and below occurrence table.

Ceiling less than 500 feet and/or Visibility less than 1 mile
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 2 % 2 % 0.9%
4 am 4 % 2 % 1 % 1 % 0 % 0 % 0 % 0 % 1 % 1 % 2 % 2 % 1.2%
7 am 4 % 3 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 2 % 3 % 2 % 1.7%
10 am 5 % 4 % 2 % 1 % 1 % 0 % 0 % 0 % 3 % 3 % 5 % 4 % 2.3%
1 pm 6 % 5 % 3 % 2 % 1 % 1 % 1 % 1 % 4 % 4 % 6 % 4 % 3.2%
4 pm 6 % 5 % 2 % 1 % 1 % 0 % 0 % 0 % 2 % 2 % 4 % 4 % 2.3%
7 pm 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 1 % 1 % 2 % 2 % 1.1%
10 pm 3 % 2 % 0 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 2 % 1 % 0.8%

 

Ceiling less than 200 feet and/or Visibility less than 1/2 mile
Hour Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Ann
1 am 1 % 1 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 1 % 0.4%
4 am 3 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 am 4 % 2 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 3 % 1.1%
10 am 6 % 4 % 1 % 1 % 0 % 0 % 0 % 0 % 0 % 2 % 3 % 3 % 1.7%
1 pm 5 % 6 % 2 % 1 % 1 % 0 % 0 % 0 % 1 % 3 % 3 % 4 % 2.2%
4 pm 3 % 3 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 2 % 0.8%
7 pm 1 % 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0.3%
10 pm 1 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 0 % 1 % 0 % 0.2%