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SunnyDays

ERA5 almanac — 8 years of real data

Naples in May

Naples in May is historically a poor month for sun: only 28% of days clear across 8 years (n=248, avg high 87°F). March is the clearest month for Naples 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 Naples 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 Naples 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		 34% n=120 87°F
Late May
16th–end		 23% n=128 87°F
Full month average 28% n=248 87°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 Naples 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		 96% n=120
Late May
16th–end		 92% n=128
Full month average 94% n=248
13.0 h median sunshine per day 90% of days exceed 8 h sunshine 48% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 28%. Sunshine-based “warm & sunny”: 94%. The 66-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

Naples is mostly overcast in May historically: only 28% of days are clear across 8 years (n=248), avg high 87°F. If you want sun in Naples, 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 Naples.

Every month in Naples

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

Historical clear-sky % for Naples, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 35% n=248 All destinations →
February 41% n=226 All destinations →
March 48% n=248 All destinations →
April 41% n=240 All destinations →
May ← this page 28% n=248 All destinations →
June 7% n=240 All destinations →
July 4% n=248 All destinations →
August 2% n=248 All destinations →
September 9% n=240 All destinations →
October 23% n=248 All destinations →
November 44% n=240 All destinations →
December 45% 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.