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SunnyDays

ERA5 almanac — 8 years of real data

Los Cabos in September

Los Cabos in September: 26% of days see measurable rain, 90°F average high, 51% of days historically clear (n=240, ERA5 2018–2025).

Los Cabos in September is a mixed month for sun: 51% of days historically clear (n=240, avg high 90°F). The outcome varies year to year — check the early/late split below. 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 Los Cabos 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 September

Clear-sky percentage for Los Cabos in September, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early September
1st–15th		 41% n=120 90°F
Late September
16th–end		 61% n=120 90°F
Full month average 51% n=240 90°F

Sunshine & warmth in September

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 Los Cabos in September. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early September
1st–15th		 92% n=120
Late September
16th–end		 97% n=120
Full month average 94% n=240
11.8 h median sunshine per day 94% of days exceed 8 h sunshine 26% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 51%. Sunshine-based “warm & sunny”: 94%. The 43-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

Los Cabos in September is genuinely mixed: 51% of days historically clear (n=240), avg high 90°F — roughly even odds. The two halves differ materially (41% early, 61% late) — favour the late half of the month. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Los Cabos

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

Historical clear-sky % for Los Cabos, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 91% n=248 All destinations →
February 88% n=226 All destinations →
March 98% n=248 All destinations →
April 99% n=240 All destinations →
May 98% n=248 All destinations →
June 92% n=240 All destinations →
July 85% n=248 All destinations →
August 55% n=248 All destinations →
September ← this page 51% n=240 All destinations →
October 80% n=248 All destinations →
November 88% n=240 All destinations →
December 89% n=248 All destinations →

Frequently asked

Does it rain in Los Cabos in September?

Sometimes. Los Cabos sees measurable rain on 26% of days in September historically (n=240 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Los Cabos good for sun in September?

It's mixed. Los Cabos in September is clear on 51% of days historically (avg high 90°F, n=240 days, ERA5 2018–2025) — the outcome varies year to year.

How Los Cabos compares in September

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Los Cabos 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.