ERA5 almanac — 8 years of real data
Where is it warm in September?
Ranked by historical clear-sky percentage from the ERA5 reanalysis (2018–2025, 55 destinations). Palm Desert leads with 94% historically clear days in this month (n=240). Every percentage below has its sample size beside it.
What you are reading: 8-year historical averages, not a forecast.
A destination that is historically 90% clear in September can still be overcast
this specific September. For this week’s actual forecast, each
destination links to its live page.
| # | Destination | Early September (1st–15th, n) |
Late September (16th–end, n) |
Month avg | Avg high | Verdict |
|---|---|---|---|---|---|---|
| 1 | Palm Desert CA | 93% (n=120) | 94% (n=120) | 94% | 101°F | Palm Desert is historically one of the clearest places in this month: 94% of days meet the clear bar on average across 8 years (n=240). |
| 2 | Palm Springs CA | 94% (n=120) | 94% (n=120) | 94% | 100°F | Palm Springs is historically one of the clearest places in this month: 94% of days meet the clear bar on average across 8 years (n=240). |
| 3 | Palm Springs Desert CA | 94% (n=120) | 94% (n=120) | 94% | 102°F | Palm Springs Desert is historically one of the clearest places in this month: 94% of days meet the clear bar on average across 8 years (n=240). |
| 4 | Las Vegas NV | 88% (n=120) | 95% (n=120) | 92% | 98°F | Las Vegas is historically one of the clearest places in this month: 92% of days meet the clear bar on average across 8 years (n=240). |
| 5 | Los Angeles CA | 87% (n=120) | 87% (n=120) | 87% | 88°F | Los Angeles is historically one of the clearest places in this month: 87% of days meet the clear bar on average across 8 years (n=240). |
| 6 | Napa CA | 93% (n=120) | 79% (n=120) | 86% | 86°F | Napa is historically one of the clearest places in this month: 86% of days meet the clear bar on average across 8 years (n=240). |
| 7 | Wine Country Sonoma CA | 92% (n=120) | 81% (n=120) | 86% | 84°F | Wine Country Sonoma is historically one of the clearest places in this month: 86% of days meet the clear bar on average across 8 years (n=240). |
| 8 | Moab UT | 80% (n=120) | 87% (n=120) | 84% | 88°F | Moab is historically one of the clearest places in this month: 84% of days meet the clear bar on average across 8 years (n=240). |
| 9 | Santa Barbara CA | 88% (n=120) | 78% (n=120) | 83% | 84°F | Santa Barbara is historically one of the clearest places in this month: 83% of days meet the clear bar on average across 8 years (n=240). |
| 10 | Phoenix AZ | 82% (n=120) | 81% (n=120) | 82% | 101°F | Phoenix is historically one of the clearest places in this month: 82% of days meet the clear bar on average across 8 years (n=240). |
| 11 | Scottsdale AZ | 83% (n=120) | 82% (n=120) | 82% | 100°F | Scottsdale is historically one of the clearest places in this month: 82% of days meet the clear bar on average across 8 years (n=240). |
| 12 | Scottsdale Desert Ridge AZ | 82% (n=120) | 82% (n=120) | 82% | 98°F | Scottsdale Desert Ridge is historically one of the clearest places in this month: 82% of days meet the clear bar on average across 8 years (n=240). |
| 13 | San Diego CA | 88% (n=120) | 70% (n=120) | 79% | 78°F | San Diego clears solidly in this month — 79% of days on average across 8 years (n=240), avg high 78°F. |
| 14 | San Luis Obispo CA | 88% (n=120) | 70% (n=120) | 79% | 80°F | San Luis Obispo clears solidly in this month — 79% of days on average across 8 years (n=240), avg high 80°F. |
| 15 | Albuquerque NM | 77% (n=120) | 76% (n=120) | 76% | 85°F | Albuquerque clears solidly in this month — 76% of days on average across 8 years (n=240), avg high 85°F. |
| 16 | Sedona AZ | 71% (n=120) | 76% (n=120) | 74% | 86°F | Sedona clears solidly in this month — 74% of days on average across 8 years (n=240), avg high 86°F. |
| 17 | Newport Beach CA | 82% (n=120) | 59% (n=120) | 70% | 76°F | Newport Beach clears solidly in this month — 70% of days on average across 8 years (n=240), avg high 76°F. |
| 18 | Tucson AZ | 72% (n=120) | 69% (n=120) | 70% | 96°F | Tucson clears solidly in this month — 70% of days on average across 8 years (n=240), avg high 96°F. |
| 19 | Marfa TX | 58% (n=120) | 71% (n=120) | 64% | 84°F | Marfa clears solidly in this month — 64% of days on average across 8 years (n=240), avg high 84°F. |
| 20 | Taos NM | 59% (n=120) | 69% (n=120) | 64% | 77°F | Taos clears solidly in this month — 64% of days on average across 8 years (n=240), avg high 77°F. |
| 21 | Santa Fe NM | 50% (n=120) | 50% (n=120) | 50% | 76°F | Santa Fe is mixed in this month: clear 50% of days historically (n=240), avg high 76°F. Check the halves — the split can be wide. |
| 22 | Dallas TX | 46% (n=120) | 51% (n=120) | 48% | 90°F | Dallas is mixed in this month: clear 48% of days historically (n=240), avg high 90°F. Check the halves — the split can be wide. |
| 23 | Lake Tahoe CA | 65% (n=120) | 31% (n=120) | 48% | 72°F | Lake Tahoe is mixed in this month: clear 48% of days historically (n=240), avg high 72°F. Check the halves — the split can be wide. |
| 24 | Nashville TN | 48% (n=120) | 47% (n=120) | 48% | 83°F | Nashville is mixed in this month: clear 48% of days historically (n=240), avg high 83°F. Check the halves — the split can be wide. |
| 25 | Charlotte NC | 47% (n=120) | 41% (n=120) | 44% | 82°F | Charlotte is mixed in this month: clear 44% of days historically (n=240), avg high 82°F. Check the halves — the split can be wide. |
| 26 | Austin TX | 35% (n=120) | 47% (n=120) | 41% | 91°F | Austin is mixed in this month: clear 41% of days historically (n=240), avg high 91°F. Check the halves — the split can be wide. |
| 27 | Asheville NC | 41% (n=120) | 38% (n=120) | 40% | 78°F | Asheville is mixed in this month: clear 40% of days historically (n=240), avg high 78°F. Check the halves — the split can be wide. |
| 28 | Outer Banks NC | 38% (n=120) | 43% (n=120) | 40% | 78°F | Outer Banks is mixed in this month: clear 40% of days historically (n=240), avg high 78°F. Check the halves — the split can be wide. |
| 29 | Aspen CO | 52% (n=120) | 26% (n=120) | 39% | 72°F | Aspen is mostly overcast this month historically: only 39% of days clear on average across 8 years (n=240), avg high 72°F. |
| 30 | San Antonio TX | 30% (n=120) | 42% (n=120) | 36% | 92°F | San Antonio is mostly overcast this month historically: only 36% of days clear on average across 8 years (n=240), avg high 92°F. |
| 31 | Big Sur CA | 40% (n=120) | 30% (n=120) | 35% | 72°F | Big Sur is mostly overcast this month historically: only 35% of days clear on average across 8 years (n=240), avg high 72°F. |
| 32 | Panama City Beach FL | 23% (n=120) | 47% (n=120) | 35% | 85°F | Panama City Beach is mostly overcast this month historically: only 35% of days clear on average across 8 years (n=240), avg high 85°F. |
| 33 | Jackson Hole WY | 48% (n=120) | 21% (n=120) | 34% | 70°F | Jackson Hole is mostly overcast this month historically: only 34% of days clear on average across 8 years (n=240), avg high 70°F. |
| 34 | Destin FL | 27% (n=120) | 39% (n=120) | 33% | 86°F | Destin is mostly overcast this month historically: only 33% of days clear on average across 8 years (n=240), avg high 86°F. |
| 35 | Hilton Head SC | 28% (n=120) | 38% (n=120) | 33% | 83°F | Hilton Head is mostly overcast this month historically: only 33% of days clear on average across 8 years (n=240), avg high 83°F. |
| 36 | Kiawah Island SC | 29% (n=120) | 37% (n=120) | 33% | 83°F | Kiawah Island is mostly overcast this month historically: only 33% of days clear on average across 8 years (n=240), avg high 83°F. |
| 37 | Charleston SC | 28% (n=120) | 37% (n=120) | 32% | 83°F | Charleston is mostly overcast this month historically: only 32% of days clear on average across 8 years (n=240), avg high 83°F. |
| 38 | Gulf Shores AL | 31% (n=120) | 33% (n=120) | 32% | 85°F | Gulf Shores is mostly overcast this month historically: only 32% of days clear on average across 8 years (n=240), avg high 85°F. |
| 39 | Savannah GA | 28% (n=120) | 37% (n=120) | 32% | 85°F | Savannah is mostly overcast this month historically: only 32% of days clear on average across 8 years (n=240), avg high 85°F. |
| 40 | Sea Island GA | 26% (n=120) | 37% (n=120) | 32% | 83°F | Sea Island is mostly overcast this month historically: only 32% of days clear on average across 8 years (n=240), avg high 83°F. |
| 41 | Houston TX | 28% (n=120) | 32% (n=120) | 30% | 88°F | Houston is mostly overcast this month historically: only 30% of days clear on average across 8 years (n=240), avg high 88°F. |
| 42 | Park City UT | 41% (n=120) | 19% (n=120) | 30% | 70°F | Park City is mostly overcast this month historically: only 30% of days clear on average across 8 years (n=240), avg high 70°F. |
| 43 | Vail CO | 38% (n=120) | 8% (n=120) | 23% | 70°F | Vail is mostly overcast this month historically: only 23% of days clear on average across 8 years (n=240), avg high 70°F. → Try August |
| 44 | Amelia Island FL | 17% (n=120) | 27% (n=120) | 22% | 84°F | Amelia Island is mostly overcast this month historically: only 22% of days clear on average across 8 years (n=240), avg high 84°F. → Try April |
| 45 | Jacksonville FL | 17% (n=120) | 27% (n=120) | 22% | 86°F | Jacksonville is mostly overcast this month historically: only 22% of days clear on average across 8 years (n=240), avg high 86°F. → Try April |
| 46 | St. Augustine FL | 11% (n=120) | 23% (n=120) | 17% | 83°F | St. Augustine is poor for sun this month: just 17% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try April |
| 47 | Tampa FL | 6% (n=120) | 18% (n=120) | 12% | 87°F | Tampa is poor for sun this month: just 12% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try April |
| 48 | Key West FL | 14% (n=120) | 8% (n=120) | 11% | 85°F | Key West is poor for sun this month: just 11% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try March |
| 49 | Sarasota FL | 6% (n=120) | 16% (n=120) | 11% | 86°F | Sarasota is poor for sun this month: just 11% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try April |
| 50 | Carmel-by-the-Sea CA | 9% (n=120) | 10% (n=120) | 10% | 67°F | Carmel-by-the-Sea is poor for sun this month: just 10% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try October |
| 51 | Orlando FL | 8% (n=120) | 13% (n=120) | 10% | 86°F | Orlando is poor for sun this month: just 10% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try March |
| 52 | Naples FL | 6% (n=120) | 12% (n=120) | 9% | 88°F | Naples is poor for sun this month: just 9% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try March |
| 53 | Fort Lauderdale FL | 3% (n=120) | 8% (n=120) | 6% | 86°F | Fort Lauderdale is poor for sun this month: just 6% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try March |
| 54 | Palm Beach FL | 5% (n=120) | 8% (n=120) | 6% | 86°F | Palm Beach is poor for sun this month: just 6% of days clear historically (n=240). The 8-year record says to look elsewhere. → Try March |
| 55 | Miami FL | 5% (n=120) | 4% (n=120) | 4% | 86°F | Miami is historically very rarely clear this month: only 4% of days meet the clear bar across 8 years (n=240). Plan for clouds. → Try March |
Honest note on the bottom of this list: Miami is historically 4% clear in September (n=240 days). That is not a soft number — it means roughly 4 days out of every 100 historically meet our clear bar here in this month. If you want Miami, try March instead.
Every month
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.