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SunnyDays

ERA5 almanac — 8 years of real data

Jacksonville in October

Jacksonville in October is historically a poor month for sun: only 33% of days clear across 8 years (n=248, avg high 79°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 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 October

Clear-sky percentage for Jacksonville in October, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early October
1st–15th		 28% n=120 79°F
Late October
16th–end		 37% n=128 79°F
Full month average 33% n=248 79°F

Sunshine & warmth in October

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 October. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early October
1st–15th		 86% n=120
Late October
16th–end		 80% n=128
Full month average 83% n=248
10.7 h median sunshine per day 84% of days exceed 8 h sunshine 30% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 33%. Sunshine-based “warm & sunny”: 83%. The 50-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 is mostly overcast in October historically: only 33% of days are clear across 8 years (n=248), avg high 79°F. Most visitors this month will see more clouds than 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 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 ← this page 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.