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SunnyDays

ERA5 almanac — 8 years of real data

Honolulu in March

Honolulu in March: 39% of days see measurable rain, 78°F average high, 22% of days historically clear (n=248, ERA5 2018–2025).

Honolulu in March is historically a poor month for sun: only 22% of days clear across 8 years (n=248, avg high 78°F). January is the clearest month for Honolulu 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 Honolulu 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 March

Clear-sky percentage for Honolulu in March, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early March
1st–15th		 20% n=120 78°F
Late March
16th–end		 24% n=128 78°F
Full month average 22% n=248 78°F

Sunshine & warmth in March

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 Honolulu in March. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early March
1st–15th		 90% n=120
Late March
16th–end		 94% n=128
Full month average 92% n=248
11.3 h median sunshine per day 89% of days exceed 8 h sunshine 39% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 22%. Sunshine-based “warm & sunny”: 92%. The 70-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

Honolulu is mostly overcast in March historically: only 22% of days are clear across 8 years (n=248), avg high 78°F. If you want sun in Honolulu, January is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in January — historically the best month for sun in Honolulu.

Every month in Honolulu

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

Historical clear-sky % for Honolulu, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 36% n=248 All destinations →
February 24% n=226 All destinations →
March ← this page 22% n=248 All destinations →
April 14% n=240 All destinations →
May 21% n=248 All destinations →
June 30% n=240 All destinations →
July 20% n=248 All destinations →
August 31% n=248 All destinations →
September 24% n=240 All destinations →
October 24% n=248 All destinations →
November 26% n=240 All destinations →
December 33% n=248 All destinations →

Frequently asked

Does it rain in Honolulu in March?

Sometimes. Honolulu sees measurable rain on 39% of days in March historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Honolulu good for sun in March?

Not usually. Honolulu is historically overcast in March: only 22% of days are clear (avg high 78°F, n=248 days, ERA5 2018–2025). January is historically far better for sun here.

How Honolulu compares in March

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Honolulu 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.