Harrisburg, IL Climate: Temperature & Rain by Month
Annual temperature and rainfall from NOAA NCEI's 1991–2020 normals →; comfort score computed by PlainClimate
30-year climate normals (1991-2020) from Harrisburg's primary NOAA station, HARRISBURG.
The climate verdict for Harrisburg
Water is the standout signal in Harrisburg, Illinois: 47.6 inches of precipitation in a normal year. Against that wet profile, NOAA records an annual average of 57°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.
- 57°F
- yearly average temperature, NOAA normal
- 80/100
- comfort score, above 76% of station-mapped location scores
- 47.6"
- yearly precipitation total
- 202 days
- frost-free growing season
Harrisburg: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00113879 · Harrisburg, IL 57°F mean · 47.6" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-MID · SWING-WIDE · COMF-TOP · LOAD-HEAT · STN-1 · BOOK-FULL
- TEMP-MILD 57°F
- RANK-UPPER #4,597
- PHOTO-FINISH ≈ Teec Nos Pos
- PRCP-MID 47.6"
- SWING-WIDE 45°F
- COMF-TOP 80/100
- LOAD-HEAT 4,299 HDD
- STN-1 USC00113879
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Teec Nos Pos, AZ ( -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.
- Harrisburg (this station) 57°F
- Cold Teec Nos Pos, AZ 57°F
- Hot Springfield, MO 57°F
- Near Miami, TX 57°F
- Near Evansville Regi…, IN 57°F
Climate Living Index · Harrisburg
Harrisburg: 69/100 · grade C
Harrisburg publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Harrisburg, not an official NOAA rating. Rankings still use Comfort Score 80/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 87 calendar days | 80/100 · B |
| Annual temperature balance | 57.3°F · 10.2° from 67.5°F | 67/100 · C |
| Frost-free season | 202 days/year | 66/100 · C |
| Precipitation balance | 47.6 in · 12.6 from 35 in | 56/100 · C |
Harrisburg · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Harrisburg is a temperate Köppen climate: Cfa
Coldest-month mean 33.4°F and warmest-month mean 78.7°F place this station in temperate, no dry season, hot summer climates (Cfa). Class Cfa is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: temperate, specifically temperate, no dry season, hot summer.
- Köppen code
- Cfa
- Group
- Temperate
- Warmest month
- 78.7°F
- Coldest month
- 33.4°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 Harrisburg sits across the climate record
Three NOAA fields for Harrisburg's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 67th percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- Top 25% wettest
- Harrisburg's annual total ranks in the wetter third of 6,352 measured normals.
- Seasonal temperature swing
- 61st percentile swing
- Typical seasonal amplitude versus 6,861 complete station-years.
How Harrisburg compares across U.S. station-mapped locations
Harrisburg'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
Harrisburg's measured station temperature trend
MethodologyAcross 74 complete annual observations from 1899 to 2024, HARRISBURG changed little at a fitted rate of 0.01°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Harrisburg primary station fitted change +0.01 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 43°F (6°C) | 24°F (-4°C) | 33°F (1°C) | 3.8" | 24.5 | 0.0 |
| February | 48°F (9°C) | 28°F (-2°C) | 38°F (3°C) | 3.1" | 19.8 | 0.0 |
| March | 58°F (15°C) | 36°F (2°C) | 47°F (8°C) | 4.9" | 12.6 | 0.0 |
| April | 69°F (21°C) | 46°F (8°C) | 58°F (14°C) | 5.3" | 2.6 | 0.4 |
| May | 78°F (26°C) | 57°F (14°C) | 67°F (20°C) | 4.3" | 0.0 | 1.1 |
| June | 86°F (30°C) | 65°F (18°C) | 76°F (24°C) | 4.9" | 0.0 | 9.2 |
| July | 89°F (32°C) | 68°F (20°C) | 79°F (26°C) | 3.5" | 0.0 | 14.1 |
| August | 88°F (31°C) | 66°F (19°C) | 77°F (25°C) | 3.6" | 0.0 | 13.1 |
| September | 82°F (28°C) | 57°F (14°C) | 70°F (21°C) | 3.1" | 0.1 | 5.1 |
| October | 71°F (22°C) | 45°F (7°C) | 58°F (15°C) | 3.8" | 2.5 | 0.3 |
| November | 57°F (14°C) | 36°F (2°C) | 47°F (8°C) | 4.0" | 11.7 | 0.0 |
| December | 47°F (8°C) | 29°F (-2°C) | 38°F (3°C) | 3.4" | 21.1 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 89°F around July 11, short of 90°F on every date, while 87 dates carry a normal low at or below freezing, the coldest 24°F near January 14.
The freezing stretch
The normal low stays at or below 32°F into February 28, then returns to freezing around December 4, covering 87 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 April 22, when 37% of years recorded at least a hundredth of an inch. The driest is August 25 at 18%. Summed across the calendar, that is about 93 wet dates a year.
The widest day
October 8 carries the biggest normal gap between afternoon and dawn, 26°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Harrisburg.
Monthly Precipitation
Average monthly rainfall
7.8 days with precipitation
6.3 days with precipitation
8.9 days with precipitation
10.9 days with precipitation
9.4 days with precipitation
7.9 days with precipitation
6.9 days with precipitation
6.0 days with precipitation
6.3 days with precipitation
6.2 days with precipitation
7.6 days with precipitation
8.1 days with precipitation
Harrisburg spreads its precipitation across the year
Neither half of the year dominates here: June through August take 25% of the annual total and December through February 22%, with neither reaching the 35% that would mark a distinct wet season. Harrisburg has no dry season to plan around, though it does carry a wide 45.3°F gap between its warmest and coldest month.
The gap between the wettest and driest month still matters: April averages 5.3" and September 3.1". The three wettest months together take 32% 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.
When it rains in Harrisburg, it arrives in quantity
47.6" of precipitation falls across only about 92 wet days here, averaging 0.52 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 92 a year, 25% of all days
- Average depth per wet day
- 0.52 inches
- Most wet days
- April, about 11
- Fewest wet days
- August, about 6
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.
Frost Dates & Growing Season
First Fall Freeze
October 26
50% probability date
Last Spring Freeze
April 7
50% probability date
Growing Season
202 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
4,299
Higher = more heating needed
Cooling Degree Days
1,522
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside IL closest to Harrisburg 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 (57°F here).
- Ash Grove, MO 57°F · 0.0°F off
- Asheville, NC 57°F · 0.0°F off
- Bentonville, AR 57°F · 0.0°F off
- Bishop, CA 57°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (47.6" here), excluding temperature-peer places.
- Cooperstown, NY 47.6" · 0.0" off
- Tarboro, NC 47.6" · 0.0" off
- Drain, OR 47.6" · 0.0" off
- Stony Creek, VA 47.6" · 0.0" off
Data-derived climate profile
How Harrisburg's climate pattern fits together
heating led · wet · mid swing
Harrisburg's energy balance leans toward cold weather: 4,299 annual heating degree days against 1,522 for cooling. Its 45.3°F seasonal range still makes the monthly rows more useful than the annual average alone.
Harrisburg's frost-free season lasts about 202 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 Harrisburg's middle-range seasonal profile. The measured spread is 45.3°F. The annual average is 57°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Alongside its heating load, Harrisburg carries 47.6 inches of precipitation in a normal year, inside PlainClimate's wet range. Snowfall is not added to the interpretation because its annual value is missing. That distinction matters because a wet annual total can arrive as rain, snow, or a mixture at different times.
These labels group NOAA 1991-2020 normals from Harrisburg'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 Harrisburg, not an official NOAA class or a year-ahead forecast.
Questions about Harrisburg's climate
How much rain does Harrisburg get? ▼
How many days above 90°F does Harrisburg get? ▼
How much energy does heating and cooling require in Harrisburg? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Harrisburg's primary station: HARRISBURG (USC00113879). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 1733136). Match rule for Harrisburg: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Harrisburg 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.