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SunnyDays

ERA5 almanac — 8 years of real data

St. Barthélemy in March

St. Barthélemy in March: 24% of days see measurable rain, 79°F average high, 29% of days historically clear (n=248, ERA5 2018–2025).

St. Barthélemy in March is historically a poor month for sun: only 29% of days clear across 8 years (n=248, avg high 79°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 St. Barthélemy 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 St. Barthélemy 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		 40% n=120 79°F
Late March
16th–end		 19% n=128 79°F
Full month average 29% n=248 79°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 St. Barthélemy 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		 100% n=120
Late March
16th–end		 100% n=128
Full month average 100% n=248
11.5 h median sunshine per day 100% of days exceed 8 h sunshine 24% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 29%. Sunshine-based “warm & sunny”: 100%. The 71-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

St. Barthélemy is mostly overcast in March historically: only 29% of days are clear across 8 years (n=248), avg high 79°F. The two halves differ materially (40% early, 19% late) — favour the early half of the month. Most visitors this month will see more clouds than sun.

Every month in St. Barthélemy

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

Historical clear-sky % for St. Barthélemy, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 18% n=248 All destinations →
February 12% n=226 All destinations →
March ← this page 29% n=248 All destinations →
April 22% n=240 All destinations →
May 21% n=248 All destinations →
June 19% n=240 All destinations →
July 10% n=248 All destinations →
August 14% n=248 All destinations →
September 13% n=240 All destinations →
October 20% n=248 All destinations →
November 19% n=240 All destinations →
December 18% n=248 All destinations →

Frequently asked

Does it rain in St. Barthélemy in March?

Sometimes. St. Barthélemy sees measurable rain on 24% of days in March historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is St. Barthélemy good for sun in March?

Not usually. St. Barthélemy is historically overcast in March: only 29% of days are clear (avg high 79°F, n=248 days, ERA5 2018–2025).

How St. Barthélemy compares in March

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