St Louis Spirit of St. Louis Airport, Missouri climate: Climate normals at a NOAA weather station
St Louis Spirit of St. Louis Airport's normal year runs from 22°F January nights to 90°F July afternoons, with 39.8 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 13.4°C, January lows of −6°C, July highs of 32°C, 1,010 mm of precipitation a year.
- NOAA stationSt Louis Spirit of St. Louis Airport
- Station IDUSW00003966
- Location38.66°N 90.66°W
- Elevation462 ft (141 m)
On October 23, the normal high in St Louis Spirit of St. Louis Airport is 67°F and the normal low 43°F, and the chance of measurable rain or snow is 30%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for St Louis Spirit of St. Louis Airport.
- Jan 41° 22°
- Feb 47° 26°
- Mar 57° 34°
- Apr 68° 44°
- May 77° 55°
- Jun 86° 64°
- Jul 90° 68°
- Aug 88° 66°
- Sep 81° 57°
- Oct 70° 45°
- Nov 56° 34°
- Dec 45° 26°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at St Louis Spirit of St. Louis Airport each month?
July is the warmest month, with normal highs of 90°F; January the coldest, with normal lows of 22°F. The most precipitation falls in April (4.58 in), the least in February (1.98 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 41°F | 22°F | 31.5°F | 2.38 | 8 | <1 | 26 | 9 h 40 min |
| February | 47°F | 26°F | 36.1°F | 1.98 | 8 | <1 | 22 | 10 h 40 min |
| March | 57°F | 34°F | 45.9°F | 3.48 | 11 | <1 | 14 | 11 h 50 min |
| April | 68°F | 44°F | 56.4°F | 4.58 | 12 | 1 | 4 | 13 h 10 min |
| May | 77°F | 55°F | 66.0°F | 4.56 | 13 | 2 | <1 | 14 h 10 min |
| June | 86°F | 64°F | 74.8°F | 4.31 | 11 | 9 | <1 | 14 h 50 min |
| July | 90°F | 68°F | 78.7°F | 3.30 | 9 | 16 | <1 | 14 h 40 min |
| August | 88°F | 66°F | 76.9°F | 3.44 | 10 | 12 | <1 | 13 h 40 min |
| September | 81°F | 57°F | 68.7°F | 3.02 | 9 | 5 | <1 | 12 h 30 min |
| October | 70°F | 45°F | 57.3°F | 3.10 | 10 | <1 | 3 | 11 h 20 min |
| November | 56°F | 34°F | 45.3°F | 3.28 | 9 | <1 | 13 | 10 h 10 min |
| December | 45°F | 26°F | 35.7°F | 2.32 | 8 | <1 | 23 | 9 h 30 min |
| Year (annual) | 67°F | 45°F | 56.1°F | 39.75 | 116 | 44 | 105 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 5°C | −6°C | −0.3°C | 60 mm |
| February | 8°C | −3°C | 2.3°C | 50 mm |
| March | 14°C | 1°C | 7.7°C | 88 mm |
| April | 20°C | 7°C | 13.6°C | 116 mm |
| May | 25°C | 13°C | 18.9°C | 116 mm |
| June | 30°C | 18°C | 23.8°C | 109 mm |
| July | 32°C | 20°C | 25.9°C | 84 mm |
| August | 31°C | 19°C | 24.9°C | 87 mm |
| September | 27°C | 14°C | 20.4°C | 77 mm |
| October | 21°C | 7°C | 14.1°C | 79 mm |
| November | 13°C | 1°C | 7.4°C | 83 mm |
| December | 7°C | −3°C | 2.1°C | 59 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Weldon Spring (3 miles away), gets 14 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003966; 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.
Which months are mildest at St Louis Spirit of St. Louis Airport?
Normal highs sit between 65°F and 85°F in April, May, September and October. Of those, September has the fewest days with rain (9).
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 USW00003966.
When is the last frost at St Louis Spirit of St. Louis Airport?
In St Louis Spirit of St. Louis Airport, the last spring frost (32°F) comes after April 12 in half of years and after April 27 in one year in ten; the first autumn frost comes before October 23 in half of years and before October 11 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 121 year in 10 after April 27; 9 in 10 after March 28
- First autumn frost, half of years before
- October 231 year in 10 before October 11; 9 in 10 before November 5
NOAA puts the median frost-free season at 193 days, and the season without a hard freeze (28°F) at 216 days.
A hard freeze (28°F) comes after March 31 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts St Louis Spirit of St. Louis Airport in zone 6b in ZIP code 63005, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 6b: the coldest night of a typical year reaches −2°F (26 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 USW00003966; 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.
How hot and how cold does it get at St Louis Spirit of St. Louis Airport?
In a normal year in St Louis Spirit of St. Louis Airport, 44 days a year reach 90°F (2 of them 100°F or more), 105 nights fall to 32°F or colder and 116 days bring measurable precipitation.
- Days at 90°F or more
- 44a normal year
- Days at 100°F or more
- 2a normal year
- Nights at 32°F or colder
- 105a normal year
- Days that stay below freezing
- 18high of 32°F or less
- Days with 0.01 inch of precipitation
- 116a normal year
The highest temperature in this station's record (since 1987) is 109°F, on June 28, 2012; the lowest is −22°F, on December 23, 1989.
The wettest calendar year on that record is 1990, with 52.73 in; the snowiest season is 1992–93, with 24.7 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00003966; records: ACIS (NOAA Regional Climate Centers), station USW00003966. Records use complete months only; a month missing more than three days is left out.
How humid and windy is it at St Louis Spirit of St. Louis Airport, and how clear are the skies?
The summer (June-August) dew point averages 66°F. The muggiest month is July, with an average dew point of 67°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 (8.2 mph on average), and September has the most clear or nearly clear hours (67%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | 23°F | 67% | 51% | 7.4 mph | 49% | 36% |
| February | 28°F | 64% | 46% | 8.2 mph | 48% | 36% |
| March | 38°F | 62% | 44% | 8.2 mph | 49% | 30% |
| April | 49°F | 67% | 49% | 7.2 mph | 47% | 31% |
| May | 60°F | 71% | 52% | 5.9 mph | 50% | 22% |
| June | 66°F | 71% | 51% | 5.3 mph | 58% | 12% |
| July | 67°F | 72% | 50% | 4.6 mph | 65% | 12% |
| August | 65°F | 73% | 49% | 4.4 mph | 66% | 13% |
| September | 52°F | 71% | 45% | 5.1 mph | 67% | 15% |
| October | 40°F | 68% | 48% | 6.6 mph | 61% | 28% |
| November | 31°F | 69% | 53% | 7.3 mph | 54% | 34% |
| December | 24°F | 70% | 56% | 7.4 mph | 51% | 38% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00003966. 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 it at St Louis Spirit of St. Louis Airport?
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds at St Louis Spirit of St. Louis Airport, 4.2 kWh per square metre a day. July is the sunniest month (82%) and December the cloudiest (66%).
| 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 many heating and cooling degree days does St Louis Spirit of St. Louis Airport record?
A normal year at St Louis Spirit of St. Louis Airport brings 4,650 heating degree days, 13% fewer than the median U.S. place (5,373), and 1,448 cooling degree days, 60% 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 4,209 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,038 | 0 |
| February | 808 | 1 |
| March | 598 | 6 |
| April | 288 | 28 |
| May | 88 | 120 |
| June | 6 | 300 |
| July | 0 | 426 |
| August | 2 | 370 |
| September | 51 | 162 |
| October | 271 | 32 |
| November | 593 | 2 |
| December | 907 | 0 |
| Year (annual) | 4,650 | 1,448 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003966. 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.
Have recent years at St Louis Spirit of St. Louis Airport been warmer than normal?
2025 averaged 56.3°F, 0.2°F above the 1991-2020 normal of 56.1°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 56.8°F | +0.7°F | 36.35 |
| 2022 | 55.4°F | −0.7°F | 40.36 |
| 2023 | 56.9°F | +0.8°F | 28.72 |
| 2024 | 57.5°F | +1.4°F | 50.51 |
| 2025 | 56.3°F | +0.2°F | 35.04 |
Over 32 complete years from 1989 to 2025, the station's annual mean temperature rose at a fitted 3.7°F per century (+0.21°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00003966; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does St Louis Spirit of St. Louis Airport's climate compare?
St Louis Spirit of St. Louis Airport is warmer than 92 of the 134 places with their own NOAA record in Missouri, and wetter than 20. Across the 7,247 U.S. stations with normals, its annual mean of 56.1°F is warmer than 64%.
In the Köppen classification computed from these normals, St Louis Spirit of St. Louis Airport is Dfa: continental, 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 Spirit of St. Louis Airport share this climate record?
9 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.
- Chesterfield, MO49,465 people · 4 mi E
- Wildwood, MO35,082 people · 6 mi S
- Ballwin, MO31,036 people · 7 mi SE
- Eureka, MO13,277 people · 11 mi S
- Ellisville, MO10,359 people · 6 mi SE
- Clarkson Valley, MO2,557 people · 4 mi SE
- Winchester, MO1,407 people · 8 mi SE
- LaBarque Creek, MO1,292 people · 17 mi S
- Lake Tekakwitha, MO236 people · 15 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about St Louis Spirit of St. Louis Airport's climate
What is the coldest month at St Louis Spirit of St. Louis Airport?
January, with a normal high of 41°F and a normal low of 22°F. The warmest is July (90°F by day, 68°F at night).
Does it snow at St Louis Spirit of St. Louis Airport?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Weldon Spring (3 miles away), records 14 inches of snow in a normal year.
What is the rainiest month at St Louis Spirit of St. Louis Airport?
April, with 4.58 in of precipitation in a normal year; the driest is February with 1.98 in.
What plant hardiness zone is St Louis Spirit of St. Louis Airport in?
The USDA's 2023 map puts St Louis Spirit of St. Louis Airport in zone 6b in ZIP code 63005, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −2°F (26 years, 1991-2020): zone 6b.
How late can frost come at St Louis Spirit of St. Louis Airport?
In half of years the last 32°F night comes after April 12; in one year in ten it comes after April 27. Waiting until April 27 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Missouri climateThe statewide normals and every place in the state
- Weldon Spring, MO3 miles from this station, 55.2°F a year
- St. Peters, MO9 miles from this station, 55.3°F a year
- St. Louis, MO17 miles from this station, 57.4°F a year
- Washington, MO19 miles from this station, 54.8°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made