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SunnyDays

ERA5 almanac — 8 years of real data

Lake Tahoe in August

Historically one of the better months to visit Lake Tahoe for sun: 80% of days are clear on average (n=248, avg high 79°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 Lake Tahoe 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 Lake Tahoe 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		 84% n=120 79°F
Late August
16th–end		 77% n=128 79°F
Full month average 80% n=248 79°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 Lake Tahoe 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		 97% n=120
Late August
16th–end		 89% n=128
Full month average 93% n=248
13.4 h median sunshine per day 98% of days exceed 8 h sunshine 7% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 80%. Sunshine-based “warm & sunny”: 93%. 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

Lake Tahoe is historically one of the best US destinations for sun in August: 80% of days meet the clear bar (avg high 79°F, n=248 days across 8 years). Pack for outdoor activity — this month consistently delivers.

Every month in Lake Tahoe

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

Historical clear-sky % for Lake Tahoe, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 0% n=248 All destinations →
April 0% n=240 All destinations →
May 5% n=248 All destinations →
June 48% n=240 All destinations →
July 85% n=248 All destinations →
August ← this page 80% n=248 All destinations →
September 48% n=240 All destinations →
October 10% n=248 All destinations →
November 0% 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.