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SunnyDays

ERA5 almanac — 8 years of real data

Nashville in August

Nashville in August is historically a poor month for sun: only 32% of days clear across 8 years (n=248, avg high 87°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 Nashville 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 August

Clear-sky percentage for Nashville in August, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early August
1st–15th		 23% n=120 87°F
Late August
16th–end		 41% n=128 87°F
Full month average 32% n=248 87°F

Sunshine & warmth in August

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 Nashville in August. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early August
1st–15th		 92% n=120
Late August
16th–end		 89% n=128
Full month average 90% n=248
12.1 h median sunshine per day 83% of days exceed 8 h sunshine 47% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 32%. Sunshine-based “warm & sunny”: 90%. The 58-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

Nashville is mostly overcast in August historically: only 32% of days are clear across 8 years (n=248), avg high 87°F. Most visitors this month will see more clouds than sun.

Every month in Nashville

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

Historical clear-sky % for Nashville, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 1% n=226 All destinations →
March 8% n=248 All destinations →
April 18% n=240 All destinations →
May 28% n=248 All destinations →
June 30% n=240 All destinations →
July 19% n=248 All destinations →
August ← this page 32% n=248 All destinations →
September 48% n=240 All destinations →
October 32% n=248 All destinations →
November 6% n=240 All destinations →
December 0% 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.