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SunnyDays

ERA5 almanac — 8 years of real data

Maui in May

Maui in May: 36% of days see measurable rain, 76°F average high, 26% of days historically clear (n=248, ERA5 2018–2025).

Maui in May is historically a poor month for sun: only 26% of days clear across 8 years (n=248, avg high 76°F). August is the clearest month for Maui 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 Maui 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 Maui 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		 22% n=120 76°F
Late May
16th–end		 30% n=128 76°F
Full month average 26% n=248 76°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 Maui 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		 81% n=120
Late May
16th–end		 96% n=128
Full month average 89% n=248
12.3 h median sunshine per day 91% of days exceed 8 h sunshine 36% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 26%. Sunshine-based “warm & sunny”: 89%. The 63-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

Maui is mostly overcast in May historically: only 26% of days are clear across 8 years (n=248), avg high 76°F. If you want sun in Maui, August is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in August — historically the best month for sun in Maui.

Every month in Maui

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

Historical clear-sky % for Maui, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 25% n=248 All destinations →
February 16% n=226 All destinations →
March 15% n=248 All destinations →
April 19% n=240 All destinations →
May ← this page 26% n=248 All destinations →
June 40% n=240 All destinations →
July 33% n=248 All destinations →
August 43% n=248 All destinations →
September 34% n=240 All destinations →
October 28% n=248 All destinations →
November 30% n=240 All destinations →
December 30% n=248 All destinations →

Frequently asked

Does it rain in Maui in May?

Sometimes. Maui sees measurable rain on 36% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Maui good for sun in May?

Not usually. Maui is historically overcast in May: only 26% of days are clear (avg high 76°F, n=248 days, ERA5 2018–2025). August is historically far better for sun here.

How Maui compares in May

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Maui this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

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.