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Best time to visit · Missouri, United States
For the most comfortable weather in Downtown St. Louis & the Arch, aim for September & October. September tops our comfort score at 90/100, with highs around 81°F (27°C) and 3.1 in (80 mm) of rain. April – June and August are good shoulder-season months. The toughest months are December – February, mainly because of cool days.
These averages also cover Forest Park & the Central West End.
Highs run from 39°F to 88°F across the year, and the yearly total is about 43.5 in (1106 mm) of rain and snow.
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high | 39°F4°C | 43°F6°C | 55°F13°C | 67°F20°C | 76°F24°C | 84°F29°C | 88°F31°C | 87°F31°C | 81°F27°C | 68°F20°C | 55°F13°C | 43°F6°C |
| Avg low | 22°F-6°C | 24°F-5°C | 34°F1°C | 45°F7°C | 56°F13°C | 65°F18°C | 69°F20°C | 67°F19°C | 59°F15°C | 46°F8°C | 34°F1°C | 26°F-3°C |
| Rain/snow | 2.5 in63 mm | 2.5 in64 mm | 3.7 in93 mm | 4.8 in121 mm | 5.1 in130 mm | 4.2 in107 mm | 4.0 in101 mm | 3.7 in93 mm | 3.1 in80 mm | 3.7 in94 mm | 3.4 in86 mm | 2.9 in74 mm |
| Humidity | 82% | 80% | 78% | 76% | 78% | 77% | 74% | 71% | 70% | 71% | 76% | 82% |
| Cloud | 62% | 65% | 63% | 57% | 60% | 50% | 47% | 47% | 43% | 50% | 54% | 64% |
| Comfort | 47 | 49 | 67 | 81 | 73 | 72 | 68 | 72 | 90 | 87 | 70 | 48 |
Source: NASA POWER (public domain), 2001–2025 monthly averages on a ~50 km satellite and reanalysis grid, so coasts and valleys can differ from what's shown. The grid cell sits at about 153 m (502 ft), close to Downtown St. Louis & the Arch's own ~146 m. Precipitation includes snow as melted water; daylight is calculated from latitude. Check a forecast before you go.
The cold peaks here: highs of 39–43°F (4–6°C), and nights reach 22°F (-6°C). It's the driest season, with only about 7.9 in (201 mm) of rain or snow, 18% of the year's total. December – February are cold enough for snow. It holds the toughest stretch on our comfort score (December – February), averaging 48/100.
Temperatures climb through the season, from 55°F highs in March to 76°F by May. It's the wettest season, with about 13.5 in (344 mm) of rain, 31% of the year's total. Lows bottom out around 34°F (1°C). April & May score well without being the very best (season average 74/100).
The warmest stretch of the year, with highs of 84–88°F (29–31°C). About 11.9 in (301 mm) of rain falls across these months, 27% of the year's total. June feels humid, with humidity near 77%. June and August score well without being the very best (season average 71/100).
Temperatures slide from 81°F highs in September to 55°F by November. About 10.2 in (260 mm) of rain falls across these months, 24% of the year's total. Lows bottom out around 34°F (1°C). September & October are among the best-scoring months (season average 82/100).
By comfort score: 3 Great, 6 Good and 3 Fair. Great months: April and September & October. Tap a month for its own guide.
For the most comfortable weather in Downtown St. Louis & the Arch, aim for September & October. September tops our comfort score at 90/100, with highs around 81°F (27°C) and 3.1 in (80 mm) of rain. April – June and August are good shoulder-season months. The toughest months are December – February, mainly because of cool days.
May is the wettest month, averaging about 5.1 in (130 mm) of rain. January is the driest, with about 2.5 in (63 mm). The yearly total is around 43.5 in (1106 mm).
January is the coldest, with average lows of 22°F (-6°C) and highs of 39°F (4°C). The warmest is July, with average highs of 88°F (31°C).
Yes: in June humidity averages 77% with warm temperatures, so it feels muggy. Summer highs peak around 88°F (31°C).
On average, yes: lows fall below 32°F (0°C) in December – February, bottoming out around 22°F (-6°C) in January.
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