Delavan Commercial Historic District · Photo: Ammodramus · CC0Delavan’s winters are colder but less snowy than most of the U.S.
A typical July afternoon reaches 86°, a January night drops to 18°, and about 19 inches of snow falls in a normal winter.
A year in Delavan at a glance
Each month’s typical high and low, and what it brings.
What stands out about Delavan’s climate
Compared with towns across the U.S., with Delavan’s place in Illinois beside it.
What a year in Delavan feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 182 frost-free days a year
In half of years the last 32° night comes by April 17 and the first by October 18. Frost and day counts come from NOAA’s station at Mason City 4se, IL, 15 miles from the town’s center, at about the same height.
The 2023 USDA map puts Delavan’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 19 inches of snow a winter
Snow, measured at Lincoln, IL, is heaviest from January through February, about 6 inches a month. Precipitation (rain plus melted snow) adds up to 39 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 118 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Delavan
85% 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 Mason City 4se, IL.
Living with Delavan’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
182 frost-free days in zone 6a. The last frost comes by Apr 17 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 18.
Months with highs of 62–84° and lows of 40° or more: April, May, June, September and October. 0.3 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Delavan from natural hazards, river flooding is the largest share (41%); heat waves, cold waves, winter storms and ice storms together are 22%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Delavan and similar climates
TownRatings has no climate map of the towns around Delavan yet.
Climates most like Delavan’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 |
|---|---|---|---|---|
| Delavan, IL | 18° | 86° | 39" | 19" |
| Savannah, MO | 18° | 87° | 37" | 21" |
| Centerville, IA | 15° | 85° | 38" | 22" |
| Van Wert, OH | 19° | 84° | 39" | 17" |
| Peru, IN | 19° | 84° | 40" | 21" |
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 Delavan averaged 1.1° warmer than the 1900s. The biggest change is in December (+2.3°).
A smaller shift than in 71% 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 Delavan compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Delavan’s place among Illinois’.
Delavan weather by month
Highs, lows and precipitation from NOAA’s grid at Delavan’s center; snow, wet days and snow on the ground from Lincoln, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 34° | 18° | 2.1" | 5.7" | 9 | 11 | 19° – 38° |
| February | 39° | 22° | 1.9" | 6.2" | 9 | 7 | 18° – 41° |
| March | 52° | 31° | 2.6" | 1.8" | 11 | 2 | 34° – 56° |
| April | 64° | 41° | 4.0" | 0.0" | 12 | 0 | 45° – 59° |
| May | 75° | 52° | 4.5" | 0.0" | 13 | 0 | 58° – 72° |
| June | 83° | 62° | 4.3" | 0.0" | 11 | 0 | 68° – 75° |
| July | 86° | 65° | 4.3" | 0.0" | 9 | 0 | 70° – 81° |
| August | 85° | 62° | 3.5" | 0.0" | 9 | 0 | 68° – 79° |
| September | 79° | 55° | 3.3" | 0.0" | 8 | 0 | 61° – 72° |
| October | 66° | 43° | 3.2" | 0.1" | 10 | 0 | 50° – 60° |
| November | 51° | 32° | 2.8" | 0.6" | 10 | 1 | 34° – 50° |
| December | 39° | 23° | 2.2" | 4.9" | 10 | 6 | 17° – 41° |
| Year | 63° | 42° | 38.6" | 19.3" | 118 | 25 |
How much a month can swing
A normal is an average. December swings the most: from 1991 to 2020 its average ranged from 17° to 41°. June is the most reliable, staying within 8°.
Where Delavan’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 Delavan’s center.
- Snow: Lincoln, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Mason City 4se, IL, 15 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 Delavan’s climate
What is the weather like in Delavan?
A typical July afternoon reaches 86°, a January night drops to 18°, and about 19 inches of snow falls in a normal winter. Colder January nights than 71% of U.S. towns; hotter July afternoons than 55% of U.S. towns.
How cold does it get in Delavan in winter?
January nights average 18°. About 122 nights a year reach 32° or below and 6 reach 0° or below. In the coldest January of the last 30 years the month averaged 19°.
How much snow does Delavan get?
About 19 inches in a normal winter at Lincoln, IL, heaviest from January through February, about 6 inches a month, with snow on the ground about 25 days a year.
How hot does it get in Delavan?
July, with a typical high of 86° and a low of 65°. About 27 days a year reach 90° (Mason City 4se, IL).
When is the first and last frost in Delavan?
In half of years the last spring frost (32°) comes by April 17 and the first fall frost by October 18, about 182 frost-free days, at Mason City 4se, IL.
What growing zone is Delavan 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 Delavan?
By one simple rule (highs of 62–84° and lows of 40° or more), April, May, June, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Delavan getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 71% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Delavan.
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.