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SunnyDays

ERA5 almanac — 8 years of real data

Jacksonville in April

Jacksonville in April is a mixed month for sun: 48% of days historically clear (n=240, avg high 79°F). The outcome varies year to year — check the early/late split below. 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 Jacksonville 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 April

Clear-sky percentage for Jacksonville in April, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early April
1st–15th		 38% n=120 79°F
Late April
16th–end		 59% n=120 79°F
Full month average 48% n=240 79°F

Sunshine & warmth in April

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 Jacksonville in April. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early April
1st–15th		 78% n=120
Late April
16th–end		 92% n=120
Full month average 85% n=240
12.1 h median sunshine per day 84% of days exceed 8 h sunshine 28% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 48%. Sunshine-based “warm & sunny”: 85%. The 37-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

Jacksonville in April is genuinely mixed: 48% of days historically clear (n=240), avg high 79°F — roughly even odds. The two halves differ materially (38% early, 59% late) — favour the late half of the month. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Jacksonville

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

Historical clear-sky % for Jacksonville, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 9% n=248 All destinations →
February 27% n=226 All destinations →
March 37% n=248 All destinations →
April ← this page 48% n=240 All destinations →
May 41% n=248 All destinations →
June 15% n=240 All destinations →
July 8% n=248 All destinations →
August 7% n=248 All destinations →
September 22% n=240 All destinations →
October 33% n=248 All destinations →
November 24% n=240 All destinations →
December 16% 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.