Hillsboro, IL Climate: Temperature & Rain by Month
Pulled from NOAA NCEI 1991–2020 normals →: climate measurements used in PlainClimate's documented score
30-year climate normals (1991-2020) from Hillsboro's primary NOAA station, HILLSBORO.
The climate verdict for Hillsboro
Hillsboro, Illinois 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
- annual average temperature (NOAA normal)
- 80/100
- comfort score, above 76% of station-mapped location scores
- 42.1"
- precipitation, annual total
- 194 days
- frost-free days per growing season
Hillsboro: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USC00114108 · Hillsboro, IL 56°F mean · 42.1" 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 #4,254
- PHOTO-FINISH ≈ St Charles Elm…
- PRCP-MID 42.1"
- SWING-WIDE 48°F
- COMF-TOP 80/100
- LOAD-HEAT 4,799 HDD
- STN-1 USC00114108
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: St Charles Elm Point, MO (+ 0 °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.
- Hillsboro (this station) 56°F
- Hot Vincennes, IN 56°F
- Near St Charles Elm…, MO 56°F
- Near Richfield, KS 56°F
- Cold Appleton City, MO 55°F
Climate Living Index · Hillsboro
Hillsboro: 68/100 · grade C
Hillsboro publishes 4 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 2 missing weights rescale to 100.
PlainClimate-derived for Hillsboro, not an official NOAA rating. Rankings still use Comfort Score 80/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Precipitation balance | 42.1 in · 7.1 from 35 in | 75/100 · B |
| Normal heat + freeze calendar | 105 calendar days | 73/100 · B |
| Annual temperature balance | 55.5°F · 12.0° from 67.5°F | 61/100 · C |
| Frost-free season | 194 days/year | 60/100 · C |
Hillsboro · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Hillsboro is a continental Köppen climate: Dfa
Coldest-month mean 29.9°F and warmest-month mean 77.6°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
- 77.6°F
- Coldest month
- 29.9°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 Hillsboro sits across the climate record
Three NOAA fields for Hillsboro's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 62nd percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- 63rd percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Wider than 71%
- Warmest-to-coldest month gap for Hillsboro is large versus 6,861 complete station-years.
How Hillsboro compares across U.S. station-mapped locations
Hillsboro'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
Hillsboro's measured station temperature trend
MethodologyAcross 80 complete annual observations from 1897 to 2025, HILLSBORO warmed at a fitted rate of 0.02°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Hillsboro primary station fitted change +0.02 °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 | 38°F (4°C) | 21°F (-6°C) | 30°F (-1°C) | 2.5" | 25.6 | 0.0 |
| February | 45°F (7°C) | 25°F (-4°C) | 35°F (2°C) | 2.6" | 20.4 | 0.0 |
| March | 55°F (13°C) | 34°F (1°C) | 45°F (7°C) | 3.0" | 13.7 | 0.0 |
| April | 68°F (20°C) | 44°F (7°C) | 56°F (13°C) | 5.0" | 3.4 | 0.1 |
| May | 78°F (25°C) | 54°F (12°C) | 66°F (19°C) | 5.1" | 0.0 | 1.5 |
| June | 86°F (30°C) | 63°F (17°C) | 75°F (24°C) | 3.8" | 0.0 | 10.7 |
| July | 89°F (32°C) | 67°F (19°C) | 78°F (25°C) | 3.7" | 0.0 | 14.3 |
| August | 87°F (31°C) | 65°F (18°C) | 76°F (24°C) | 3.1" | 0.0 | 10.5 |
| September | 82°F (28°C) | 57°F (14°C) | 69°F (21°C) | 3.3" | 0.1 | 5.0 |
| October | 70°F (21°C) | 46°F (8°C) | 58°F (14°C) | 3.4" | 2.5 | 0.3 |
| November | 55°F (13°C) | 35°F (2°C) | 45°F (7°C) | 3.8" | 11.8 | 0.0 |
| December | 43°F (6°C) | 26°F (-3°C) | 35°F (1°C) | 2.6" | 22.7 | 0.0 |
The year, day by day
Summer here tops out rather than builds: the warmest normal high is 89°F around July 6, short of 90°F on every date, while 105 dates carry a normal low at or below freezing, the coldest 21°F near January 17.
The freezing stretch
The normal low stays at or below 32°F into March 8, then returns to freezing around November 25, covering 105 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 4, when 36% of years recorded at least a hundredth of an inch. The driest is January 26 at 19%. Summed across the calendar, that is about 91 wet dates a year.
The widest day
September 26 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 Hillsboro.
Monthly Precipitation
Average monthly rainfall
6.3 days with precipitation
6.3 days with precipitation
8.4 days with precipitation
9.6 days with precipitation
11.2 days with precipitation
8.6 days with precipitation
7.3 days with precipitation
6.6 days with precipitation
5.9 days with precipitation
7.3 days with precipitation
6.6 days with precipitation
6.8 days with precipitation
Hillsboro 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 18%, with neither reaching the 35% that would mark a distinct wet season. Hillsboro has no dry season to plan around, though it does carry a wide 47.7°F gap between its warmest and coldest month.
The gap between the wettest and driest month still matters: May averages 5.1" and January 2.5". The three wettest months together take 33% 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 Hillsboro, it arrives in quantity
42.1" of precipitation falls across only about 91 wet days here, averaging 0.46 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 91 a year, 25% of all days
- Average depth per wet day
- 0.46 inches
- Most wet days
- May, about 11
- Fewest wet days
- September, 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 24
50% probability date
Last Spring Freeze
April 13
50% probability date
Growing Season
194 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
4,799
Higher = more heating needed
Cooling Degree Days
1,389
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
Nationwide similar cities
Other rankable U.S. places outside IL closest to Hillsboro 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).
- Allardt, TN 56°F · 0.0°F off
- Castle Valley, UT 56°F · 0.0°F off
- Hayesville, NC 56°F · 0.0°F off
- Hugoton, KS 56°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (42.1" here), excluding temperature-peer places.
- Bristow, OK 42.1" · 0.0" off
- Lancaster, PA 42.1" · 0.0" off
- Richmond, MO 42.1" · 0.0" off
- Shelbina, MO 42.1" · 0.0" off
Data-derived climate profile
How Hillsboro's climate pattern fits together
heating led · moderate · mid swing
Hillsboro's energy balance leans toward cold weather: 4,799 annual heating degree days against 1,389 for cooling. Its 47.7°F seasonal range still makes the monthly rows more useful than the annual average alone.
Hillsboro's frost-free season lasts about 194 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 Hillsboro's middle-range seasonal profile. The measured spread is 47.7°F. The annual average is 56°F. Neither the annual mean nor one extreme month represents the full calendar on its own.
Hillsboro's 42.1 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 Hillsboro'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 Hillsboro, not an official NOAA class or a year-ahead forecast.
Questions about Hillsboro's climate
How much rain does Hillsboro get? ▼
How many days above 90°F does Hillsboro get? ▼
How much energy does heating and cooling require in Hillsboro? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Hillsboro's primary station: HILLSBORO (USC00114108). 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 1735047). Match rule for Hillsboro: 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 Hillsboro 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.