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SunnyDays

ERA5 almanac — 8 years of real data

Jamaica in May

Jamaica in May: 78% of days see measurable rain, 86°F average high, 3% of days historically clear (n=248, ERA5 2018–2025).

Jamaica in May is historically a poor month for sun: only 3% of days clear across 8 years (n=248, avg high 86°F). January is the clearest month for Jamaica 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 Jamaica 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 Jamaica 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		 4% n=120 86°F
Late May
16th–end		 3% n=128 86°F
Full month average 3% n=248 86°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 Jamaica 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		 99% n=120
Late May
16th–end		 91% n=128
Full month average 95% n=248
12.0 h median sunshine per day 93% of days exceed 8 h sunshine 78% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 3%. Sunshine-based “warm & sunny”: 95%. The 92-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

Jamaica is historically almost never clear in May: only 3% of days meet the clear bar across 8 years (n=248). Come back in January if you want clear skies here. Plan entirely around indoor or overcast-friendly activities.

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

Every month in Jamaica

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

Historical clear-sky % for Jamaica, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 23% n=248 All destinations →
February 19% n=226 All destinations →
March 21% n=248 All destinations →
April 8% n=240 All destinations →
May ← this page 3% n=248 All destinations →
June 14% n=240 All destinations →
July 18% n=248 All destinations →
August 11% n=248 All destinations →
September 4% n=240 All destinations →
October 4% n=248 All destinations →
November 15% n=240 All destinations →
December 21% n=248 All destinations →

Frequently asked

Does it rain in Jamaica in May?

Yes, frequently. In Jamaica, 78% of days in May see measurable rain, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

Is Jamaica good for sun in May?

Not usually. Jamaica is historically overcast in May: only 3% of days are clear (avg high 86°F, n=248 days, ERA5 2018–2025). January is historically far better for sun here.

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.