Skip to main content
SunnyDays

ERA5 almanac — 8 years of real data

Cayman Islands in January

Cayman Islands in January: 45% of days see measurable rain, 81°F average high, 19% of days historically clear (n=248, ERA5 2018–2025).

Cayman Islands in January is historically a poor month for sun: only 19% of days clear across 8 years (n=248, avg high 81°F). 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 Cayman Islands 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 January

Clear-sky percentage for Cayman Islands in January, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early January
1st–15th		 17% n=120 81°F
Late January
16th–end		 21% n=128 81°F
Full month average 19% n=248 81°F

Sunshine & warmth in January

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 Cayman Islands in January. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early January
1st–15th		 98% n=120
Late January
16th–end		 98% n=128
Full month average 98% n=248
10.9 h median sunshine per day 95% of days exceed 8 h sunshine 45% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 19%. Sunshine-based “warm & sunny”: 98%. The 79-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

Cayman Islands is a poor choice for sun in January: just 19% of days clear historically (n=248). The 8-year record is consistent — this is not a fluke bad stretch.

Every month in Cayman Islands

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

Historical clear-sky % for Cayman Islands, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January ← this page 19% n=248 All destinations →
February 11% n=226 All destinations →
March 17% n=248 All destinations →
April 10% n=240 All destinations →
May 5% n=248 All destinations →
June 4% n=240 All destinations →
July 2% n=248 All destinations →
August 4% n=248 All destinations →
September 4% n=240 All destinations →
October 5% n=248 All destinations →
November 12% n=240 All destinations →
December 12% n=248 All destinations →

Frequently asked

Does it rain in Cayman Islands in January?

Sometimes. Cayman Islands sees measurable rain on 45% of days in January historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Cayman Islands good for sun in January?

Not usually. Cayman Islands is historically overcast in January: only 19% of days are clear (avg high 81°F, n=248 days, ERA5 2018–2025).

How Cayman Islands compares in January

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