ERA5 almanac — 8 years of real data

Honolulu in March

Honolulu in March: rain frequency data not yet backfilled for this month, 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

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

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.

→ Honolulu live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in March — all destinations ranked by March clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

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.