St Charles County, MO Climate: Temperature & Rain by Month
Explore NOAA NCEI's 1991–2020 climate normals → and a clearly labeled PlainClimate comfort calculation
30-year climate normals (1991-2020) from St Charles County's primary NOAA station, ST CHARLES CO AP.
The climate verdict for St Charles County
St Charles County, Missouri has a mixed annual climate rather than one dominant extreme. Its NOAA normal shows an annual average of 56°F. It scores 80/100 for climate comfort (excellent), putting it in the top third of station-mapped location scores and exceeding 76% of them.
- 56°F
- average temperature, NOAA 1991-2020 normal
- 80/100
- comfort score, above 76% of station-mapped location scores
- 39.4"
- precipitation, annual total
- 205 days
- frost-free growing season
St Charles County: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00053904 · St Charles County, MO 56°F mean · 39.4" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-MID · SWING-WIDE · COMF-TOP · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-MILD 56°F
- RANK-UPPER #4,391
- PHOTO-FINISH ≈ Columbia
- PRCP-MID 39.4"
- SWING-WIDE 48°F
- COMF-TOP 80/100
- LOAD-HEAT 4,681 HDD
- STN-1 USW00053904
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Columbia, MO ( -0.1 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every MO station list.
- St Charles Coun… (this station) 56°F
- Cold Columbia, MO 56°F
- Hot Columbia U of M, MO 56°F
- Near Humboldt, KS 56°F
- Near Mound Valley, KS 56°F
Climate Living Index · St Charles County
St Charles County: 71/100 · grade B
St Charles County publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for St Charles County, not an official NOAA rating. Rankings still use Comfort Score 80/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 39.4 in · 4.4 from 35 in | 84/100 · B |
| Normal heat + freeze calendar | 106 calendar days | 73/100 · B |
| Frost-free season | 205 days/year | 68/100 · C |
| Annual temperature balance | 56.1°F · 11.4° from 67.5°F | 63/100 · C |
St Charles County · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
St Charles County is a continental Köppen climate: Dfa
Coldest-month mean 30.8°F and warmest-month mean 78.6°F place this station in continental, no dry season, hot summer climates (Dfa). Class Dfa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: continental, specifically continental, no dry season, hot summer.
- Köppen code
- Dfa
- Group
- Continental
- Warmest month
- 78.6°F
- Coldest month
- 30.8°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where St Charles County sits across the climate record
Three NOAA fields for St Charles County's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 64th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- 57th percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Wider than 72%
- Warmest-to-coldest month gap for St Charles County is large versus 6,861 complete station-years.
How St Charles County compares across U.S. station-mapped locations
St Charles County's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
80 Top 24% score exceeds 76% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). Below this entry.
- 70–80: 650 station-mapped locations (11%). Below this entry.
- 80–90: 921 station-mapped locations (15%). This entry sits in this band.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 40°F (4°C) | 22°F (-6°C) | 31°F (-1°C) | 2.5" | 26.3 | 0.0 |
| February | 45°F (7°C) | 26°F (-4°C) | 35°F (2°C) | 1.9" | 21.9 | 0.0 |
| March | 56°F (14°C) | 34°F (1°C) | 45°F (7°C) | 3.1" | 13.5 | 0.0 |
| April | 68°F (20°C) | 45°F (7°C) | 57°F (14°C) | 4.2" | 2.2 | 0.4 |
| May | 77°F (25°C) | 56°F (13°C) | 67°F (19°C) | 4.6" | 0.0 | 1.8 |
| June | 86°F (30°C) | 65°F (18°C) | 75°F (24°C) | 4.5" | 0.0 | 9.6 |
| July | 89°F (32°C) | 68°F (20°C) | 79°F (26°C) | 3.7" | 0.0 | 14.8 |
| August | 88°F (31°C) | 66°F (19°C) | 77°F (25°C) | 3.7" | 0.0 | 11.9 |
| September | 81°F (27°C) | 57°F (14°C) | 69°F (21°C) | 3.0" | 0.0 | 4.8 |
| October | 69°F (21°C) | 46°F (8°C) | 58°F (14°C) | 2.7" | 2.2 | 0.4 |
| November | 55°F (13°C) | 35°F (1°C) | 45°F (7°C) | 3.1" | 12.3 | 0.0 |
| December | 44°F (7°C) | 27°F (-3°C) | 36°F (2°C) | 2.4" | 23.5 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 89°F around July 8, short of 90°F on every date, while 106 dates carry a normal low at or below freezing, the coldest 21°F near January 19.
The freezing stretch
The normal low stays at or below 32°F into March 8, then returns to freezing around November 24, covering 106 dates in all.
Derived from the normal daily minimum. This is a different measure from the 50%-probability frost dates shown elsewhere on this page, which come from NOAA’s frost product.
Where the wet dates fall
The likeliest wet date is May 25, when 41% of years recorded at least a hundredth of an inch. The driest is January 20 at 23%. Summed across the calendar, that is about 113 wet dates a year.
The widest day
September 19 carries the biggest normal gap between afternoon and dawn, 24°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for St Charles County.
Monthly Precipitation
Average monthly rainfall
7.0 days with precipitation
7.2 days with precipitation
10.8 days with precipitation
10.7 days with precipitation
12.9 days with precipitation
11.1 days with precipitation
9.2 days with precipitation
9.4 days with precipitation
9.6 days with precipitation
9.6 days with precipitation
8.0 days with precipitation
8.2 days with precipitation
St Charles County spreads its precipitation across the year
Neither half of the year dominates here: June through August take 30% of the annual total and December through February 17%, with neither reaching the 35% that would mark a distinct wet season. St Charles County has no dry season to plan around, though it does carry a wide 47.8°F gap between its warmest and coldest month.
The gap between the wettest and driest month still matters: May averages 4.6" and February 1.9". The three wettest months together take 34% of the year, against the 25% a perfectly flat distribution would give them.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. "Spread across the year" means neither the June-August nor the December-February share reaches 35%; it describes an average year, not the variability of any single one.
How St Charles County's precipitation splits across the calendar
About 114 days a year record measurable precipitation here, carrying 39.4" between them, or roughly 0.35 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Frost Dates & Growing Season
First Fall Freeze
October 27
50% probability date
Last Spring Freeze
April 5
50% probability date
Growing Season
205 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
4,681
Higher = more heating needed
Cooling Degree Days
1,465
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside MO closest to St Charles County on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (56°F here).
- Bushland, TX 56°F · 0.0°F off
- Colorado City, AZ 56°F · 0.0°F off
- Cullowhee, NC 56°F · 0.0°F off
- Franklin, NC 56°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (39.4" here), excluding temperature-peer places.
- Grand Rapids, MI 39.4" · 0.0" off
- Lawrence, KS 39.4" · 0.0" off
- Normal, IL 39.4" · 0.0" off
- Altona, IL 39.4" · 0.0" off
Data-derived climate profile
How St Charles County's climate pattern fits together
heating led · moderate · mid swing
St Charles County's energy balance leans toward cold weather: 4,681 annual heating degree days against 1,465 for cooling. Its 47.8°F seasonal range still makes the monthly rows more useful than the annual average alone.
St Charles County's frost-free season lasts about 205 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
July and January mark the typical warm and cold ends of the calendar in St Charles County's middle-range seasonal profile. The measured spread is 47.8°F. The annual average is 56°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
St Charles County's 39.4 inches of annual precipitation falls in PlainClimate's middle band, so “wet” or “dry” is not the leading description. Snowfall is not added to the interpretation because its annual value is missing. Temperature balance and the calendar distribution carry more information than the annual moisture label alone.
These labels group NOAA 1991-2020 normals from St Charles County's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for St Charles County, not an official NOAA class or a year-ahead forecast.
Questions about St Charles County's climate
How much rain does St Charles County get? ▼
How many days above 90°F does St Charles County get? ▼
How much energy does heating and cooling require in St Charles County? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from St Charles County's primary station: ST CHARLES CO AP (USW00053904). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The conservative exact name-and-state crosswalk finds no Census place match, so PlainClimate treats this as a station-mapped location and does not claim it is a municipality. No exact Gazetteer row for St Charles County; facility counts that depend on place identity are therefore an upper bound, not a municipal census.
On this page every temperature, precipitation, and derived score for St Charles County comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.