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SunnyDays

ERA5 almanac — 8 years of real data

Key West in June

Key West in June is historically a poor month for sun: only 14% of days clear across 8 years (n=240, avg high 84°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 June

Clear-sky percentage for Key West in June, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early June
1st–15th		 12% n=120 84°F
Late June
16th–end		 16% n=120 84°F
Full month average 14% n=240 84°F

Sunshine & warmth in June

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for Key West in June. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early June
1st–15th		 91% n=120
Late June
16th–end		 98% n=120
Full month average 94% n=240
12.7 h median sunshine per day 90% of days exceed 8 h sunshine 58% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 14%. Sunshine-based “warm & sunny”: 94%. The 80-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

Bottom line

Key West is a poor choice for sun in June: just 14% of days clear historically (n=240). March is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ 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 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 ← this page 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.