Photo: Ken Lund from Reno, Nevada, USA · CC BY-SA 2.0Winter nights in Diamond are colder than in 79% of U.S. towns
In July the day’s top temperature is typically 85°. It is a dry place: less rain and snow fall here than on 68% of U.S. towns. The latest 30-year average runs 1.5° warmer than 1901–2000’s, with December up the most. Garden chairs stay out from May to June and August to October, the months with highs of 65–83°.
A year in Diamond at a glance
Each month’s typical high and low, and what it brings.
What stands out about Diamond’s climate
Compared with towns across the U.S., with Diamond’s place in Illinois beside it.
What a year in Diamond feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 191 frost-free days a year
In half of years the last 32° night comes by April 16 and the first by October 26. Frost and day counts come from NOAA’s station at Channahon Dresden Isl Dam, IL, 8 miles from the town’s center, at about the same height.
The 2023 USDA map puts Diamond’s center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −10°. 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 Channahon Dresden Isl Dam, IL, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 38 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 120 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Diamond
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 Channahon Dresden Isl Dam, IL.
Living with Diamond’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
191 frost-free days in zone 5b. The last frost comes by Apr 16 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 26.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 0.0 miles of trails are waiting.
Parks & trails →Cold waves are 57% of the yearly building losses FEMA expects in Diamond from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Diamond and its neighbors
Every town next door is within a degree of Diamond in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Diamond’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 |
|---|---|---|---|---|
| Diamond, IL | 16° | 85° | 38" | 18" |
| Van Wert, OH | 19° | 84° | 39" | 17" |
| Burlington, IA | 16° | 86° | 38" | 22" |
| Bluffton, IN | 19° | 84° | 41" | 23" |
| Kirksville, MO | 17° | 86° | 41" | 19" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Diamond averaged 1.5° warmer than the 1900s. The biggest change is in December (+2.7°).
A bigger shift than in 57% 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 Diamond compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Diamond’s place among Illinois’.
Diamond weather by month
Highs, lows and precipitation from NOAA’s grid at Diamond’s center; snow, wet days and snow on the ground from Channahon Dresden Isl Dam, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 32° | 16° | 2.1" | 6.4" | 12 | 15° – 36° |
| February | 36° | 20° | 1.8" | 5.2" | 10 | 15° – 39° |
| March | 49° | 30° | 2.3" | 0.4" | 11 | 30° – 54° |
| April | 62° | 39° | 3.6" | 0.0" | 11 | 42° – 57° |
| May | 73° | 50° | 4.7" | 0.0" | 11 | 55° – 69° |
| June | 82° | 60° | 4.5" | 0.0" | 10 | 67° – 75° |
| July | 85° | 64° | 4.1" | 0.0" | 9 | 69° – 80° |
| August | 83° | 62° | 3.8" | 0.0" | 9 | 67° – 78° |
| September | 77° | 54° | 3.3" | 0.0" | 8 | 60° – 70° |
| October | 65° | 43° | 3.1" | 0.0" | 9 | 49° – 59° |
| November | 49° | 32° | 2.5" | 0.3" | 10 | 33° – 49° |
| December | 37° | 22° | 2.0" | 6.1" | 12 | 15° – 40° |
| Year | 61° | 41° | 38.0" | 18.4" | 120 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 15° to 40°. June is the most reliable, staying within 8°.
Where Diamond’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 Diamond’s center.
- Snow: Channahon Dresden Isl Dam, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Channahon Dresden Isl Dam, IL, 8 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 Diamond’s climate
What is the weather like in Diamond?
A typical July afternoon reaches 85°, a January night drops to 16°, and about 18 inches of snow falls in a normal winter. Colder January nights than 79% of U.S. towns; cooler July afternoons than 55% of U.S. towns.
How cold does it get in Diamond in winter?
January nights average 16°. About 127 nights a year reach 32° or below and 7 reach 0° or below. In the coldest January of the last 30 years the month averaged 15°.
How much snow does Diamond get?
About 18 inches in a normal winter at Channahon Dresden Isl Dam, IL, most of it in January and December.
How hot does it get in Diamond?
July, with a typical high of 85° and a low of 64°. About 21 days a year reach 90° (Channahon Dresden Isl Dam, IL).
When is the first and last frost in Diamond?
In half of years the last spring frost (32°) comes by April 16 and the first fall frost by October 26, about 191 frost-free days, at Channahon Dresden Isl Dam, IL.
What growing zone is Diamond in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −10°.
What is the best time of year to visit Diamond?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Diamond getting warmer?
Yes: 1991–2020 averaged 1.5° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 57% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Diamond.
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.