Skip to main content
SunnyDays

ERA5 almanac — 8 years of real data

Key West in January

Key West in January is historically a poor month for sun: only 27% of days clear across 8 years (n=248, avg high 72°F). March is the clearest month for Key West historically. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Key West page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late January

Clear-sky percentage for Key West in January, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early January
1st–15th		 32% n=120 72°F
Late January
16th–end		 23% n=128 72°F
Full month average 27% n=248 72°F

Bottom line

Key West is mostly overcast in January historically: only 27% of days are clear across 8 years (n=248), avg high 72°F. If you want sun in Key West, March is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in March — historically the best month for sun in Key West.

Every month in Key West

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Key West, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January ← this page 27% n=248 All destinations →
February 37% n=226 All destinations →
March 45% n=248 All destinations →
April 44% n=240 All destinations →
May 33% n=248 All destinations →
June 14% n=240 All destinations →
July 17% n=248 All destinations →
August 13% n=248 All destinations →
September 11% n=240 All destinations →
October 13% n=248 All destinations →
November 30% n=240 All destinations →
December 41% n=248 All destinations →

All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.