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SunnyDays

ERA5 almanac — 8 years of real data

New Orleans in September

New Orleans in September: 50% of days see measurable rain, 86°F average high, 28% of days historically clear (n=240, ERA5 2018–2025).

New Orleans in September is historically a poor month for sun: only 28% of days clear across 8 years (n=240, avg high 86°F). October is the clearest month for New Orleans 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 New Orleans 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 New Orleans 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		 22% n=120 86°F
Late September
16th–end		 35% n=120 86°F
Full month average 28% n=240 86°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 New Orleans 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		 87% n=120
Late September
16th–end		 89% n=120
Full month average 88% n=240
11.8 h median sunshine per day 84% of days exceed 8 h sunshine 50% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 28%. Sunshine-based “warm & sunny”: 88%. The 60-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

New Orleans is mostly overcast in September historically: only 28% of days are clear across 8 years (n=240), avg high 86°F. If you want sun in New Orleans, October is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in October — historically the best month for sun in New Orleans.

Every month in New Orleans

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

Historical clear-sky % for New Orleans, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 2% n=248 All destinations →
February 6% n=226 All destinations →
March 15% n=248 All destinations →
April 34% n=240 All destinations →
May 30% n=248 All destinations →
June 14% n=240 All destinations →
July 7% n=248 All destinations →
August 15% n=248 All destinations →
September ← this page 28% n=240 All destinations →
October 42% n=248 All destinations →
November 20% n=240 All destinations →
December 6% n=248 All destinations →

Frequently asked

Does it rain in New Orleans in September?

Yes, frequently. In New Orleans, 50% of days in September see measurable rain, based on 8 years of ERA5 historical data (n=240 days, 2018–2025). This is a historical average, not a forecast.

Is New Orleans good for sun in September?

Not usually. New Orleans is historically overcast in September: only 28% of days are clear (avg high 86°F, n=240 days, ERA5 2018–2025). October is historically far better for sun here.

How New Orleans compares in September

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against New Orleans 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.