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SunnyDays

ERA5 almanac — 8 years of real data

New York City in May

New York City in May: 41% of days see measurable rain, 71°F average high, 24% of days historically clear (n=248, ERA5 2018–2025).

New York City in May is historically a poor month for sun: only 24% of days clear across 8 years (n=248, avg high 71°F). September is the clearest month for New York City 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 New York City 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 New York City 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		 18% n=120 71°F
Late May
16th–end		 30% n=128 71°F
Full month average 24% n=248 71°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 New York City 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		 28% n=120
Late May
16th–end		 54% n=128
Full month average 41% n=248
12.5 h median sunshine per day 71% of days exceed 8 h sunshine 41% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 24%. Sunshine-based “warm & sunny”: 41%. The 17-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

New York City is mostly overcast in May historically: only 24% of days are clear across 8 years (n=248), avg high 71°F. If you want sun in New York City, September is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in September — historically the best month for sun in New York City.

Every month in New York City

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

Historical clear-sky % for New York City, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 0% n=248 All destinations →
April 6% n=240 All destinations →
May ← this page 24% n=248 All destinations →
June 39% n=240 All destinations →
July 31% n=248 All destinations →
August 35% n=248 All destinations →
September 40% n=240 All destinations →
October 13% n=248 All destinations →
November 2% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in New York City in May?

Sometimes. New York City sees measurable rain on 41% of days in May historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is New York City good for sun in May?

Not usually. New York City is historically overcast in May: only 24% of days are clear (avg high 71°F, n=248 days, ERA5 2018–2025). September is historically far better for sun here.

How New York City compares in May

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against New York City 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.