Photo: Omnedon · Public domainNeither notably warm, cold, wet nor dry, Allerton sits near the middle of U.S. towns
Deep winter brings January lows near 19°. Its January nights bite harder than in 66% of U.S. towns. Warming shows here too: 1.2° more than in 1901–2000, led by December. Tender plants can go out after about April 19; in half of years the first frost comes by October 19.
A year in Allerton at a glance
Each month’s typical high and low, and what it brings.
What stands out about Allerton’s climate
Compared with towns across the U.S., with Allerton’s place in Illinois beside it.
What a year in Allerton feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 181 frost-free days a year
In half of years the last 32° night comes by April 19 and the first by October 19. Frost and day counts come from NOAA’s station at Sidell 4n, IL, 7 miles from the town’s center, at about the same height.
The 2023 USDA map puts Allerton’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −9°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 18 inches of snow a winter
Snow, measured at Newman 3w, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 41 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 94 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Allerton
86% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Sidell 4n, IL.
Living with Allerton’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
181 frost-free days in zone 6a. The last frost comes by Apr 19 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 19.
Months with highs of 62–84° and lows of 40° or more: April, May, June, August, September and October. 0.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Allerton from natural hazards, river flooding is the largest share (35%); heat waves, cold waves, winter storms and ice storms together are 19%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Allerton and similar climates
TownRatings has no climate map of the towns around Allerton yet.
Climates most like Allerton’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Allerton, IL | 19° | 85° | 41" | 18" |
| Cambridge, OH | 21° | 85° | 41" | 17" |
| Kirksville, MO | 17° | 86° | 41" | 19" |
| Monaca, PA | 21° | 84° | 40" | 20" |
| Fort Madison, IA | 17° | 86° | 39" | 18" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Allerton averaged 1.2° warmer than the 1900s. The biggest change is in December (+2.2°).
A smaller shift than in 65% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Allerton compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Allerton’s place among Illinois’.
Allerton weather by month
Highs, lows and precipitation from NOAA’s grid at Allerton’s center; snow, wet days and snow on the ground from Newman 3w, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 35° | 19° | 2.4" | 7.7" | 8 | 20° – 39° |
| February | 40° | 23° | 2.0" | 4.1" | 6 | 19° – 42° |
| March | 51° | 31° | 2.9" | 2.0" | 8 | 34° – 55° |
| April | 64° | 41° | 4.2" | 0.0" | 9 | 45° – 59° |
| May | 74° | 52° | 4.5" | 0.0" | 10 | 57° – 71° |
| June | 83° | 61° | 4.9" | 0.0" | 9 | 68° – 75° |
| July | 85° | 65° | 4.3" | 0.0" | 7 | 70° – 81° |
| August | 84° | 62° | 3.3" | 0.0" | 7 | 68° – 79° |
| September | 79° | 55° | 3.1" | 0.0" | 6 | 61° – 72° |
| October | 66° | 43° | 3.4" | 0.0" | 7 | 50° – 60° |
| November | 51° | 33° | 3.3" | 0.5" | 8 | 35° – 49° |
| December | 39° | 24° | 2.4" | 3.8" | 8 | 18° – 41° |
| Year | 63° | 42° | 40.6" | 18.1" | 94 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 18° to 41°. June is the most reliable, staying within 8°.
Where Allerton’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Allerton’s center.
- Snow: Newman 3w, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Sidell 4n, IL, 7 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Allerton’s climate
What is the weather like in Allerton?
A typical July afternoon reaches 85°, a January night drops to 19°, and about 18 inches of snow falls in a normal winter. Colder January nights than 66% of U.S. towns; hotter July afternoons than 51% of U.S. towns.
How cold does it get in Allerton in winter?
January nights average 19°. About 126 nights a year reach 32° or below and 8 reach 0° or below. In the coldest January of the last 30 years the month averaged 20°.
How much snow does Allerton get?
About 18 inches in a normal winter at Newman 3w, IL, most of it in January.
How hot does it get in Allerton?
July, with a typical high of 85° and a low of 65°. About 23 days a year reach 90° (Sidell 4n, IL).
When is the first and last frost in Allerton?
In half of years the last spring frost (32°) comes by April 19 and the first fall frost by October 19, about 181 frost-free days, at Sidell 4n, IL.
What growing zone is Allerton in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −9°.
What is the best time of year to visit Allerton?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Allerton getting warmer?
Yes: 1991–2020 averaged 1.2° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 65% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Allerton.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.