Mt Carroll, IL Climate: Temperature & Rain by Month
Average temperature and precipitation from NOAA NCEI 1991–2020 normals →, with a derived climate comfort score
30-year climate normals (1991-2020) from Mt Carroll's primary NOAA station, MT CARROLL.
The climate verdict for Mt Carroll
Mt Carroll, Illinois has a mixed annual climate rather than one dominant extreme. Its NOAA normal shows an annual average of 49°F. Its climate comfort score of 59/100 (moderate) lands mid-pack nationally, exceeding 37% of station-mapped location scores.
- 49°F
- annual average temperature (NOAA normal)
- 59/100
- comfort score, above 37% of station-mapped location scores
- 40.3"
- annual precipitation · 33" snow
- 158 days
- frost-free growing season
Mt Carroll: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00115901 · Mt Carroll, IL 49°F mean · 40.3" precip
TEMP-COOL · RANK-COOL · PHOTO-FINISH · PRCP-MID · SWING-WIDE · COMF-MID · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-COOL 49°F
- RANK-COOL #2,333
- PHOTO-FINISH ≈ McHenry -wg Str…
- PRCP-MID 40.3"
- SWING-WIDE 52°F
- COMF-MID 59/100
- LOAD-HEAT 6,733 HDD
- STN-1 USC00115901
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: McHenry -wg Stratton L&d, IL (+ 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 IL station list.
- Mt Carroll (this station) 49°F
- Hot Thermopolis, WY 49°F
- Near McHenry -wg Str…, IL 49°F
- Near Antioch, IL 49°F
- Cold Cambridge, ID 48°F
Climate Living Index · Mt Carroll
Mt Carroll: 45/100 · grade D
Mt Carroll publishes 5 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 1 missing weight rescale to 100.
PlainClimate-derived for Mt Carroll, not an official NOAA rating. Rankings still use Comfort Score 59/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 40.3 in · 5.3 from 35 in | 81/100 · B |
| Normal heat + freeze calendar | 153 calendar days | 44/100 · D |
| Snowfall burden | 33.4 inches/year | 35/100 · F |
| Annual temperature balance | 48.5°F · 19.0° from 67.5°F | 34/100 · F |
| Frost-free season | 158 days/year | 32/100 · F |
Mt Carroll · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Mt Carroll is a continental Köppen climate: Dfa
Coldest-month mean 20.8°F and warmest-month mean 72.6°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
- 72.6°F
- Coldest month
- 20.8°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 Mt Carroll sits across the climate record
Three NOAA fields for Mt Carroll's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 34th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- 59th percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Wider than 85%
- Warmest-to-coldest month gap for Mt Carroll is large versus 6,861 complete station-years.
How Mt Carroll compares across U.S. station-mapped locations
Mt Carroll's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
59 37th percentile score exceeds 37% 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%). This entry sits in this band.
- 60–70: 1,236 station-mapped locations (20%). Above this entry.
- 70–80: 650 station-mapped locations (11%). Above this entry.
- 80–90: 921 station-mapped locations (15%). Above this entry.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Mt Carroll's measured station temperature trend
MethodologyAcross 93 complete annual observations from 1889 to 2025, MT CARROLL warmed at a fitted rate of 0.05°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Mt Carroll primary station fitted change +0.05 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 31°F (-1°C) | 11°F (-12°C) | 21°F (-6°C) | 1.7" | 10.2" | 30.0 | 0.0 |
| February | 35°F (2°C) | 14°F (-10°C) | 25°F (-4°C) | 1.8" | 7.9" | 26.6 | 0.0 |
| March | 48°F (9°C) | 26°F (-4°C) | 37°F (3°C) | 2.5" | 3.6" | 23.6 | 0.0 |
| April | 61°F (16°C) | 36°F (2°C) | 48°F (9°C) | 3.9" | 0.8" | 11.3 | 0.0 |
| May | 72°F (22°C) | 47°F (8°C) | 60°F (15°C) | 4.6" | 0.0" | 1.6 | 1.0 |
| June | 82°F (28°C) | 57°F (14°C) | 69°F (21°C) | 5.5" | 0.0" | 0.0 | 4.8 |
| July | 85°F (29°C) | 60°F (16°C) | 73°F (23°C) | 4.9" | 0.0" | 0.0 | 6.8 |
| August | 83°F (29°C) | 58°F (15°C) | 71°F (22°C) | 3.9" | 0.0" | 0.0 | 4.3 |
| September | 77°F (25°C) | 50°F (10°C) | 63°F (17°C) | 3.7" | 0.0" | 1.0 | 2.0 |
| October | 64°F (18°C) | 38°F (3°C) | 51°F (11°C) | 3.0" | 0.4" | 10.4 | 0.1 |
| November | 49°F (9°C) | 27°F (-3°C) | 38°F (3°C) | 2.6" | 1.7" | 21.2 | 0.0 |
| December | 36°F (2°C) | 17°F (-8°C) | 26°F (-3°C) | 2.2" | 8.8" | 28.8 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 85°F around July 11, short of 90°F on every date, while 153 dates carry a normal low at or below freezing, the coldest 10°F near January 23.
The freezing stretch
The normal low stays at or below 32°F into April 4, then returns to freezing around November 4, covering 153 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 29, when 41% of years recorded at least a hundredth of an inch. The driest is February 4 at 27%. Summed across the calendar, that is about 113 wet dates a year.
The widest day
September 23 carries the biggest normal gap between afternoon and dawn, 28°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Mt Carroll.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 10.2"
8.9 days with precipitation
Snow: 7.9"
7.6 days with precipitation
Snow: 3.6"
8.9 days with precipitation
Snow: 0.8"
11.4 days with precipitation
12.7 days with precipitation
11.6 days with precipitation
8.9 days with precipitation
8.7 days with precipitation
8.6 days with precipitation
Snow: 0.4"
8.7 days with precipitation
Snow: 1.7"
8.1 days with precipitation
Snow: 8.8"
9.2 days with precipitation
Mt Carroll runs a summer-peaked wet season
35% of Mt Carroll's yearly precipitation falls in June, July and August alone, against the 25% an evenly spread year would give those three months. The wettest month is June at 5.5", on a wide 51.8°F gap between its warmest and coldest month. Warm-season convection and, across the Southwest, the North American monsoon produce this shape: rain arrives in short heavy bursts during the hottest part of the year rather than as long cool-season soaking.
- Wettest three months: June, July, May, taking 37% of the annual total between them.
- Driest month: January at 1.7".
- Winter share: 14% falls in December, January and February.
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A summer-peaked label means the June-August share reaches 35%; it describes timing across an average year, not any single season, and says nothing about how heavy an individual storm can be.
When it rains in Mt Carroll, it arrives in quantity
40.3" of precipitation falls across only about 113 wet days here, averaging 0.36 inches each. Fewer days carry more water: the year's total is delivered in comparatively heavy events rather than persistent damp.
- Days with measurable precipitation
- about 113 a year, 31% of all days
- Average depth per wet day
- 0.36 inches
- Most wet days
- May, about 13
- Fewest wet days
- February, about 8
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year, and a per-day average is not a forecast of any individual storm.
Winter brings real snow to Mt Carroll
Mt Carroll averages 33.4 inches of snowfall a year, with January the snowiest month on the normals, spread across roughly 17 days that record measurable snow. That is depth accumulating on the ground, which is why it can exceed the annual precipitation figure: precipitation counts the liquid the snow melts down to, and fresh snow is mostly air.
- Annual snowfall: 33.4 inches of depth.
- Days recording measurable snow: about 17 a year.
- At a rough ten-to-one melt ratio, snow accounts for on the order of 8% of the year's precipitation.
NOAA 1991-2020 normals. The ten-to-one ratio is a convention, not a measurement: real ratios vary with temperature, so treat the share as an order of magnitude rather than an exact split.
Frost Dates & Growing Season
First Fall Freeze
October 7
50% probability date
Last Spring Freeze
May 2
50% probability date
Growing Season
158 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
6,733
Higher = more heating needed
Cooling Degree Days
746
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside IL closest to Mt Carroll 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 (49°F here).
- Butler, PA 49°F · 0.0°F off
- Decorah, IA 49°F · 0.0°F off
- Fredericktown, OH 49°F · 0.0°F off
- Grosse Pointe Farms, MI 49°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (40.3" here), excluding temperature-peer places.
- Couderay, WI 40.3" · 0.0" off
- Rutland, VT 40.3" · 0.0" off
- Beaver Falls, PA 40.3" · 0.0" off
- Petersburg, WV 40.3" · 0.0" off
Snow and freeze rhythm
When cold and snow define Mt Carroll
heating led · moderate · mid swing
Mt Carroll's energy balance leans toward cold weather: 6,733 annual heating degree days against 746 for cooling. Its 51.8°F seasonal range still makes the monthly rows more useful than the annual average alone.
Mt Carroll's frost-free season lasts about 158 days, a middle-length window whose endpoints matter more than the annual average. It describes freeze probability, not year-specific planting conditions.
-
1. Mt Carroll coldest normal
January
Averaging 21°F (-6°C), this month sits below freezing for the month as a whole, not merely overnight.
-
2. Mt Carroll typical freeze period
January through December
The station reports average freezing days from January through December.
-
3. Mt Carroll snow peak
January
Mt Carroll averages 33.4 inches of snow a year, with January the snowiest month on the normals.
Questions about Mt Carroll's climate
How much snow does Mt Carroll get? ▼
How cold does Mt Carroll get in winter? ▼
How much energy does heating and cooling require in Mt Carroll? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Mt Carroll's primary station: MT CARROLL (USC00115901). 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 Mt Carroll; 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 Mt Carroll 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.