St. Louis, Missouri climate: Normal weather by month, frost dates and records
St. Louis's normal year runs from 24°F January nights to 90°F July afternoons, with 41.7 inches of precipitation and 17 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 14.1°C, January lows of −5°C, July highs of 32°C, 1,059 mm of precipitation a year.
- NOAA stationSt Louis Lambert International Airport
- Station IDUSW00013994
- Location38.75°N 90.37°W
- Elevation531 ft (162 m)
- From the center11 miles
- Population279,695
On October 23, the normal high in St. Louis is 66°F and the normal low 46°F, and the chance of measurable rain or snow is 29%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for St. Louis.
- Jan 40° 24°
- Feb 46° 28°
- Mar 57° 37°
- Apr 68° 47°
- May 77° 58°
- Jun 86° 67°
- Jul 90° 71°
- Aug 88° 69°
- Sep 81° 61°
- Oct 69° 49°
- Nov 56° 37°
- Dec 45° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in St. Louis each month?
July is the warmest month, with normal highs of 90°F; January the coldest, with normal lows of 24°F. The most precipitation falls in May (4.82 in), the least in February (2.23 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 40°F | 24°F | 32.1°F | 2.59 | 5.7 | 9 | <1 | 24 | 9 h 40 min |
| February | 46°F | 28°F | 36.7°F | 2.23 | 4.3 | 9 | <1 | 19 | 10 h 40 min |
| March | 57°F | 37°F | 46.6°F | 3.50 | 2.3 | 11 | <1 | 10 | 11 h 50 min |
| April | 68°F | 47°F | 57.5°F | 4.73 | 0.2 | 12 | <1 | 1 | 13 h 10 min |
| May | 77°F | 58°F | 67.5°F | 4.82 | 0.0 | 13 | 2 | <1 | 14 h 10 min |
| June | 86°F | 67°F | 76.5°F | 4.49 | 0.0 | 10 | 11 | <1 | 14 h 50 min |
| July | 90°F | 71°F | 80.4°F | 3.93 | 0.0 | 9 | 16 | <1 | 14 h 40 min |
| August | 88°F | 69°F | 78.8°F | 3.38 | 0.0 | 8 | 13 | <1 | 13 h 40 min |
| September | 81°F | 61°F | 71.0°F | 2.96 | 0.0 | 7 | 5 | <1 | 12 h 30 min |
| October | 69°F | 49°F | 59.1°F | 3.15 | 0.0 | 9 | <1 | 1 | 11 h 20 min |
| November | 56°F | 37°F | 46.5°F | 3.42 | 0.9 | 9 | <1 | 9 | 10 h 10 min |
| December | 45°F | 29°F | 36.5°F | 2.50 | 3.2 | 9 | <1 | 20 | 9 h 30 min |
| Year (annual) | 67°F | 48°F | 57.4°F | 41.70 | 16.6 | 114 | 47 | 85 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 5°C | −5°C | 0.1°C | 66 mm | 14 cm |
| February | 8°C | −2°C | 2.6°C | 57 mm | 11 cm |
| March | 14°C | 3°C | 8.1°C | 89 mm | 6 cm |
| April | 20°C | 8°C | 14.2°C | 120 mm | 1 cm |
| May | 25°C | 14°C | 19.7°C | 122 mm | 0 cm |
| June | 30°C | 20°C | 24.7°C | 114 mm | 0 cm |
| July | 32°C | 22°C | 26.9°C | 100 mm | 0 cm |
| August | 31°C | 21°C | 26.0°C | 86 mm | 0 cm |
| September | 27°C | 16°C | 21.7°C | 75 mm | 0 cm |
| October | 21°C | 10°C | 15.1°C | 80 mm | 0 cm |
| November | 13°C | 3°C | 8.1°C | 87 mm | 2 cm |
| December | 7°C | −2°C | 2.5°C | 64 mm | 8 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00013994; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit St. Louis?
Normal highs sit between 65°F and 85°F in April, May, September and October. Of those, September has the fewest days with rain (7).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00013994.
When is the last frost in St. Louis?
In St. Louis, the last spring frost (32°F) comes after April 2 in half of years and after April 17 in one year in ten; the first autumn frost comes before November 4 in half of years and before October 23 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 21 year in 10 after April 17; 9 in 10 after March 17
- First autumn frost, half of years before
- November 41 year in 10 before October 23; 9 in 10 before November 18
NOAA puts the median frost-free season at 215 days, and the season without a hard freeze (28°F) at 236 days.
A hard freeze (28°F) comes after March 23 in half of springs and before November 13 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts St. Louis in zone 7a across its 20 ZIP code areas (7a in 63110, the largest). By the map's own method, the average of each year's coldest night over 1991-2020, St. Louis's NOAA station is in zone 7a: the coldest night of a typical year reaches 1°F (30 complete years).
Frost dates for every NOAA station in Missouri · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00013994; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each St. Louis ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. St. Louis's 20 ZIP code areas are all in zone 7a. Each ZIP's frost dates are in the frost tool.
| ZIP code | Zone | Land in St. Louis |
|---|---|---|
| 63101 | 7a | 0.9 km² |
| 63102 | 7a | 3.7 km² |
| 63103 | 7a | 5.7 km² |
| 63104 | 7a | 8.7 km² |
| 63106 | 7a | 5.8 km² |
| 63107 | 7a | 6.1 km² |
| 63108 | 7a | 5.8 km² |
| 63109 | 7a | 9.2 km² |
| 63110 | 7a | 17.0 km² |
| 63111 | 7a | 8.3 km² |
| 63112 | 7a | 8.2 km² |
| 63113 | 7a | 6.7 km² |
| 63115 | 7a | 11.1 km² |
| 63116 | 7a | 14.0 km² |
| 63118 | 7a | 8.8 km² |
| 63120 | 7a | 5.8 km² |
| 63137 | 7a | 2.7 km² |
| 63139 | 7a | 9.9 km² |
| 63143 | 7a | 1.4 km² |
| 63147 | 7a | 15.4 km² |
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in St. Louis?
In a normal year in St. Louis, 47 days a year reach 90°F (3 of them 100°F or more), 85 nights fall to 32°F or colder and 114 days bring measurable precipitation.
- Days at 90°F or more
- 47a normal year
- Days at 100°F or more
- 3a normal year
- Nights at 32°F or colder
- 85a normal year
- Days that stay below freezing
- 19high of 32°F or less
- Days with 0.01 inch of precipitation
- 114a normal year
- Days with 1 inch of snow or more
- 5a normal year
The highest temperature in St. Louis's official record (kept by the National Weather Service since 1874) is 115°F, on July 14, 1954; the lowest is −22°F, on January 5, 1884.
The wettest calendar year on that record is 2015, with 61.24 in; the snowiest season is 1911–12, with 67.6 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00013994; records: ACIS (NOAA Regional Climate Centers), NWS threaded record STLthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is St. Louis, and how clear are its skies?
The summer (June-August) dew point averages 65°F. The muggiest month is July, with an average dew point of 66°F, above the 65°F at which most people call the air sticky; the driest air comes in January (23°F). February is the windiest month (10.4 mph on average), and September has the most clear or nearly clear hours (53%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 23°F | 65% | 52% | 9.5 mph | 31% | 42% |
| February | 28°F | 62% | 49% | 10.4 mph | 32% | 42% |
| March | 38°F | 59% | 46% | 10.3 mph | 31% | 36% |
| April | 48°F | 62% | 48% | 9.6 mph | 28% | 38% |
| May | 59°F | 64% | 50% | 8.4 mph | 27% | 30% |
| June | 65°F | 64% | 49% | 7.8 mph | 40% | 19% |
| July | 66°F | 65% | 49% | 7.1 mph | 39% | 18% |
| August | 64°F | 66% | 49% | 7.0 mph | 44% | 17% |
| September | 52°F | 63% | 44% | 7.8 mph | 53% | 18% |
| October | 40°F | 64% | 49% | 8.9 mph | 39% | 33% |
| November | 31°F | 66% | 54% | 9.6 mph | 33% | 40% |
| December | 24°F | 69% | 58% | 9.4 mph | 32% | 45% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00013994. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is St. Louis?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around St. Louis, 4.2 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (66%). Among the 459 U.S. places of 50,000 or more, that ranks tied 304th (with 25 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 2.1 |
| February | 66% | 2.8 |
| March | 67% | 3.8 |
| April | 73% | 5.0 |
| May | 74% | 5.6 |
| June | 81% | 6.4 |
| July | 82% | 6.3 |
| August | 81% | 5.6 |
| September | 81% | 4.8 |
| October | 76% | 3.4 |
| November | 72% | 2.4 |
| December | 66% | 1.8 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does St. Louis need?
A normal year in St. Louis brings 4,433 heating degree days, 17% fewer than the median U.S. place (5,373), and 1,713 cooling degree days, 89% more than the median (908). Five months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 4,590 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,020 | 0 |
| February | 793 | 1 |
| March | 576 | 7 |
| April | 262 | 37 |
| May | 72 | 150 |
| June | 4 | 351 |
| July | 0 | 476 |
| August | 1 | 428 |
| September | 32 | 212 |
| October | 229 | 48 |
| November | 560 | 3 |
| December | 884 | 0 |
| Year (annual) | 4,433 | 1,713 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00013994. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has St. Louis been warmer than normal lately?
2025 averaged 58.6°F, 1.2°F above the 1991-2020 normal of 57.4°F. 5 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 59.0°F | +1.6°F | 42.48 | 12.6 |
| 2022 | 57.8°F | +0.4°F | 48.94 | 15.0 |
| 2023 | 60.4°F | +3.0°F | 33.14 | 3.0 |
| 2024 | 61.1°F | +3.7°F | 50.81 | 12.4 |
| 2025 | 58.6°F | +1.2°F | 38.77 | 25.2 |
Over 83 complete years from 1939 to 2025, the station's annual mean temperature rose at a fitted 2.4°F per century (+0.13°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00013994; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does St. Louis's climate compare?
St. Louis is warmer than 114 of the other 133 places with their own NOAA record in Missouri, and wetter than 41. Across the 7,247 U.S. stations with normals, its annual mean of 57.4°F is warmer than 68%.
In the Köppen classification computed from these normals, St. Louis is Cfa: temperate, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near St. Louis share this climate record?
11 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Maryland Heights, MO27,671 people · 6 mi SW
- Hazelwood, MO24,951 people · 3 mi N
- St. Ann, MO12,704 people · 2 mi S
- Bridgeton, MO11,301 people · 3 mi NW
- Berkeley, MO8,058 people · 2 mi E
- St. John, MO6,472 people · 3 mi SE
- Breckenridge Hills, MO4,369 people · 3 mi S
- Woodson Terrace, MO3,888 people · 2 mi SE
- Edmundson, MO848 people · 1 mi S
- Kinloch, MO262 people · 3 mi E
- Champ, MO7 people · 4 mi W
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do St. Louis's other NOAA stations record?
2 more NOAA stations keep 1991-2020 normals in or near St. Louis. This page uses St Louis Lambert International Airport; the others differ by site and elevation, and the linked ones have pages of their own:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| St Louis Science Center USC00237452 | 1 mi W | 515 ft | 58.0°F | 25°F | 90°F | 43.9 | – | April 1 |
| St Louis Spirit of St. Louis Airport USW00003966 | 22 mi W | 462 ft | 56.1°F | 22°F | 90°F | 39.8 | – | April 12 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about St. Louis's climate
What is the coldest month in St. Louis?
January, with a normal high of 40°F and a normal low of 24°F. The warmest is July (90°F by day, 71°F at night).
Does it snow in St. Louis?
Yes: 17 inches in a normal year, falling on 15 days with 0.1 inch or more, the most in January (5.7 inches).
What is the rainiest month in St. Louis?
May, with 4.82 in of precipitation in a normal year; the driest is February with 2.23 in.
What plant hardiness zone is St. Louis in?
The USDA's 2023 map puts St. Louis in zone 7a across its 20 ZIP code areas (7a in 63110, the largest). By the same method at St. Louis's NOAA station, the coldest night of a typical year reaches 1°F (30 years, 1991-2020): zone 7a.
How late can frost come in St. Louis?
In half of years the last 32°F night comes after April 2; in one year in ten it comes after April 17. Waiting until April 17 leaves about a one-in-ten chance of a later frost.
Nearby and next
- St. Louis in OctoberThis month day by day, its records and recent years
- Missouri climateThe statewide normals and every place in the state
- St Louis Science Center, MO10 miles from this station, 58.0°F a year
- St. Peters, MO12 miles from this station, 55.3°F a year
- St. Charles, MO12 miles from this station, 56.1°F a year
- Alton, IL14 miles from this station, 55.7°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made