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SunnyDays

ERA5 almanac — 8 years of real data

Tampa in December

Tampa in December is historically a poor month for sun: only 34% of days clear across 8 years (n=248, avg high 72°F). 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 Tampa 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 December

Clear-sky percentage for Tampa in December, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early December
1st–15th		 39% n=120 72°F
Late December
16th–end		 30% n=128 72°F
Full month average 34% n=248 72°F

Sunshine & warmth in December

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 Tampa in December. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early December
1st–15th		 58% n=120
Late December
16th–end		 44% n=128
Full month average 51% n=248
9.5 h median sunshine per day 72% of days exceed 8 h sunshine 23% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 34%. Sunshine-based “warm & sunny”: 51%. The 17-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

Tampa is mostly overcast in December historically: only 34% of days are clear across 8 years (n=248), avg high 72°F. Most visitors this month will see more clouds than sun.

Every month in Tampa

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

Historical clear-sky % for Tampa, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 23% n=248 All destinations →
February 40% n=226 All destinations →
March 52% n=248 All destinations →
April 54% n=240 All destinations →
May 38% n=248 All destinations →
June 6% n=240 All destinations →
July 2% n=248 All destinations →
August 2% n=248 All destinations →
September 12% n=240 All destinations →
October 41% n=248 All destinations →
November 41% n=240 All destinations →
December ← this page 34% 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.