Florissant, Missouri climate: NOAA's gridded normals for the city, beside the nearest station records
NOAA's gridded 1991-2020 normals put Florissant's center at January lows of 23°F and July highs of 88°F, a yearly mean of 56.1°F and 42.0 inches of precipitation. No NOAA station keeps a record under the city's name. The nearest station record, Alton (11 miles NE, 405 ft), has January lows of 22°F and July highs of 87°F.
51,290 people (Census Bureau 2024). Distances and directions are from the city's center.
- Jan 39° 23°
- Feb 45° 27°
- Mar 55° 35°
- Apr 67° 45°
- May 76° 56°
- Jun 85° 65°
- Jul 88° 69°
- Aug 87° 67°
- Sep 80° 59°
- Oct 68° 47°
- Nov 55° 37°
- Dec 44° 28°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
The months above are NOAA's gridded normals at Florissant's center.
What is each month like in Florissant?
NOAA's grid estimates the normals every 5 km or so from the stations around each point, terrain included. It smooths between stations, so night lows at the heart of a large city can run warmer than the grid shows: at five big-city airports we compared, the grid's highs were within about 1°F of the station and its lows 1-6°F cooler. The nearest record's high and low are beside each month.
| Month | High | Low | Mean | Precip. | Alton high | Alton low |
|---|---|---|---|---|---|---|
| January | 39°F | 23°F | 31.1°F | 2.46 | 39°F | 22°F |
| February | 45°F | 27°F | 35.7°F | 2.19 | 44°F | 25°F |
| March | 55°F | 35°F | 45.4°F | 3.38 | 54°F | 35°F |
| April | 67°F | 45°F | 56.1°F | 4.70 | 66°F | 45°F |
| May | 76°F | 56°F | 66.2°F | 4.95 | 75°F | 56°F |
| June | 85°F | 65°F | 75.0°F | 4.37 | 84°F | 66°F |
| July | 88°F | 69°F | 78.5°F | 3.95 | 87°F | 69°F |
| August | 87°F | 67°F | 76.8°F | 3.53 | 86°F | 67°F |
| September | 80°F | 59°F | 69.4°F | 3.34 | 80°F | 60°F |
| October | 68°F | 47°F | 57.8°F | 3.19 | 68°F | 48°F |
| November | 55°F | 37°F | 45.6°F | 3.39 | 54°F | 37°F |
| December | 44°F | 28°F | 35.6°F | 2.58 | 44°F | 27°F |
In metric: a yearly mean of 13.4°C, January lows of −5°C, July highs of 31°C and 1,068 mm of precipitation a year.
Source: NOAA NCEI U.S. Monthly Gridded Climate Normals 1991-2020 (nClimGrid, accession 0245564); NOAA NCEI 1991-2020 station normals. The grid cell holding the city's Census center point.
What do the station records around Florissant say?
Each row is a NOAA station's own 1991-2020 normals, with the snow and frost dates the grid does not give. A record downhill or nearer the coast than the city can run warmer, one uphill cooler: compare the elevations.
| Record | Where | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| AltonAlton - Melvin Price Lock and Dam | 11 mi NE | 405 ft | 55.7°F | 22°F | 87°F | 41.9 | – | April 4 |
| St. LouisSt Louis Lambert International Airport | 4 mi SW | 531 ft | 57.4°F | 24°F | 90°F | 41.7 | 17 | April 2 |
| St. CharlesSt Charles County Airport | 10 mi NW | 436 ft | 56.1°F | 22°F | 89°F | 39.4 | – | April 5 |
Source: NOAA NCEI 1991-2020 U.S. Climate Normals; place center and population: Census Bureau 2024. Last frost: the median last spring date of 32°F.
How much snow, how late a frost, what zone and how much sun in Florissant?
NOAA's grid gives no snow, frost dates or records, so these come from the nearest station record, Alton (11 miles NE, 405 ft). NOAA publishes no snowfall normal for it; the nearest record that has one, St. Louis (4 miles SW), gets 17 inches a year. The last spring frost (32°F) comes after April 4 in half of years and the first autumn frost before November 5. Its record high is 116°F (1946) and its record low −16°F (1983) (kept since 1943).
The USDA's 2023 Plant Hardiness Zone Map puts Florissant in zone 7a across its 2 ZIP code areas.
Over a year 75% of the sunlight that would reach the ground under clear skies gets through the clouds in the area (4.2 kWh per square metre a day, NASA POWER 2001-2020); July is the sunniest month (82%) and December the cloudiest (66%).
Alton's page has its months, frost probabilities, records by month and recent years. NOAA's grid has monthly figures only, so there are no day-by-day month pages for Florissant; the nearest record's month pages have them.
Source: NOAA NCEI 1991-2020 normals, station USC00110137; records: ACIS; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; sunshine: NASA POWER.
How does the climate vary across Florissant, ZIP code by ZIP code?
2 ZIP code areas lie wholly or partly in Florissant. On NOAA's grid 63031 is the warmest (56.1°F a year) and 63033 the coolest (56.1°F), so the city is nearly uniform. Each row also names the nearest station record and its frost dates.
Source: Census Bureau 2020 ZCTA-to-place relationship file and ZCTA centers; NOAA NCEI gridded and station normals, 1991-2020. A ZIP area counts when at least a tenth of its land (and 0.5 km²) is in the city; its figures are the grid cell at its center; frost dates are the nearest record's medians of 32°F.