Skip to main content
SunnyDays

ERA5 almanac — 8 years of real data

Santa Barbara in September

Historically one of the better months to visit Santa Barbara for sun: 83% of days are clear on average (n=240, avg high 84°F). Every percentage here is a historical average from 8 years of ERA5 data — 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 Santa Barbara 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 Santa Barbara 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		 88% n=120 84°F
Late September
16th–end		 78% n=120 84°F
Full month average 83% n=240 84°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 Santa Barbara 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		 100% n=120
Late September
16th–end		 92% n=120
Full month average 96% n=240
11.9 h median sunshine per day 96% of days exceed 8 h sunshine 6% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 83%. Sunshine-based “warm & sunny”: 96%. The 13-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

Santa Barbara is historically one of the best US destinations for sun in September: 83% of days meet the clear bar (avg high 84°F, n=240 days across 8 years). Pack for outdoor activity — this month consistently delivers.

Every month in Santa Barbara

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

Historical clear-sky % for Santa Barbara, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 19% n=248 All destinations →
February 22% n=226 All destinations →
March 19% n=248 All destinations →
April 48% n=240 All destinations →
May 46% n=248 All destinations →
June 70% n=240 All destinations →
July 93% n=248 All destinations →
August 96% n=248 All destinations →
September ← this page 83% n=240 All destinations →
October 81% n=248 All destinations →
November 48% n=240 All destinations →
December 19% n=248 All destinations →

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.