Skip to main content
SunnyDays

ERA5 almanac — 8 years of real data

Miami in May

Miami in May is historically a poor month for sun: only 20% of days clear across 8 years (n=248, avg high 85°F). March is the clearest month for Miami 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 Miami 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 May

Clear-sky percentage for Miami in May, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early May
1st–15th		 23% n=120 85°F
Late May
16th–end		 18% n=128 85°F
Full month average 20% n=248 85°F

Sunshine & warmth in May

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 Miami in May. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early May
1st–15th		 94% n=120
Late May
16th–end		 88% n=128
Full month average 91% n=248
12.9 h median sunshine per day 89% of days exceed 8 h sunshine 57% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 20%. Sunshine-based “warm & sunny”: 91%. The 71-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

Miami is mostly overcast in May historically: only 20% of days are clear across 8 years (n=248), avg high 85°F. If you want sun in Miami, 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 Miami.

Every month in Miami

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

Historical clear-sky % for Miami, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 28% n=248 All destinations →
February 26% n=226 All destinations →
March 32% n=248 All destinations →
April 27% n=240 All destinations →
May ← this page 20% n=248 All destinations →
June 2% n=240 All destinations →
July 6% n=248 All destinations →
August 2% n=248 All destinations →
September 4% n=240 All destinations →
October 11% n=248 All destinations →
November 25% n=240 All destinations →
December 28% 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.