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SunnyDays

ERA5 almanac — 8 years of real data

Miami in January

Miami in January is historically a poor month for sun: only 28% of days clear across 8 years (n=248, avg high 75°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 January

Clear-sky percentage for Miami 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		 30% n=120 75°F
Late January
16th–end		 26% n=128 75°F
Full month average 28% n=248 75°F

Sunshine & warmth in January

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 January. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early January
1st–15th		 72% n=120
Late January
16th–end		 70% n=128
Full month average 71% n=248
10.2 h median sunshine per day 81% of days exceed 8 h sunshine 33% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 28%. Sunshine-based “warm & sunny”: 71%. The 43-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 January historically: only 28% of days are clear across 8 years (n=248), avg high 75°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 ← this page 28% n=248 All destinations →
February 26% n=226 All destinations →
March 32% n=248 All destinations →
April 27% n=240 All destinations →
May 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.