Photo: IvoShandor · CC BY-SA 3.0Marseilles’ winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 85°, a January night drops to 16°, and about 25 inches of snow falls in a normal winter.
A year in Marseilles at a glance
Each month’s typical high and low, and what it brings.
What stands out about Marseilles’ climate
Compared with towns across the U.S., with Marseilles’ place in Illinois beside it.
What a year in Marseilles feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 171 frost-free days a year
In half of years the last 32° night comes by April 27 and the first by October 17. Frost and day counts come from NOAA’s station at Marseilles Lock, IL, 4 miles from the town’s center, 100 ft lower.
The 2023 USDA map puts Marseilles’ center in zone 5b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −11°. 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 25 inches of snow a winter
Snow, measured at Marseilles Lock, IL, falls mostly in January. Precipitation (rain plus melted snow) adds up to 37 inches a year; May is the wettest month and February the driest. Rain or snow falls on about 124 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Marseilles
89% 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 Marseilles Lock, IL.
Living with Marseilles’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
171 frost-free days in zone 5b. The last frost comes by Apr 27 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 17.
Months with highs of 62–84° and lows of 40° or more: May, June, August, September and October. 9.8 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Marseilles from natural hazards, river flooding is the largest share (70%); heat waves, cold waves, winter storms and ice storms together are 17%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Marseilles and its neighbors
Every town next door is within a degree of Marseilles in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Marseilles’, 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 |
|---|---|---|---|---|
| Marseilles, IL | 16° | 85° | 37" | 25" |
| Mount Pleasant, IA | 15° | 85° | 38" | 25" |
| Defiance, OH | 19° | 85° | 37" | 24" |
| Auburn, IN | 17° | 84° | 38" | 30" |
| Adrian, MI | 17° | 84° | 34" | 26" |
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 Marseilles averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.6°).
A bigger shift than in 52% 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 Marseilles compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Marseilles’ place among Illinois’.
Marseilles weather by month
Highs, lows and precipitation from NOAA’s grid at Marseilles’ center; snow, wet days and snow on the ground from Marseilles Lock, IL. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 31° | 16° | 2.0" | 8.4" | 11 | 15 | 15° – 35° |
| February | 36° | 20° | 1.8" | 7.3" | 10 | 11 | 15° – 39° |
| March | 49° | 29° | 2.3" | 2.9" | 11 | 4 | 30° – 54° |
| April | 62° | 39° | 3.6" | 0.3" | 12 | 0 | 42° – 57° |
| May | 73° | 50° | 4.6" | 0.0" | 12 | 0 | 55° – 68° |
| June | 82° | 59° | 4.4" | 0.0" | 11 | 0 | 67° – 75° |
| July | 85° | 64° | 3.9" | 0.0" | 9 | 0 | 69° – 81° |
| August | 83° | 62° | 3.8" | 0.0" | 9 | 0 | 67° – 78° |
| September | 78° | 54° | 3.3" | 0.0" | 8 | 0 | 60° – 70° |
| October | 65° | 42° | 3.1" | 0.0" | 10 | 0 | 49° – 59° |
| November | 49° | 31° | 2.5" | 0.8" | 10 | 1 | 32° – 49° |
| December | 37° | 21° | 2.0" | 5.3" | 11 | 9 | 15° – 40° |
| Year | 61° | 41° | 37.3" | 25.0" | 124 | 39 |
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 Marseilles’ 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 Marseilles’ center.
- Snow: Marseilles Lock, IL.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Marseilles Lock, IL, 4 miles from the town’s center, 100 ft lower; 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 Marseilles’ climate
What is the weather like in Marseilles?
A typical July afternoon reaches 85°, a January night drops to 16°, and about 25 inches of snow falls in a normal winter. Colder January nights than 82% of U.S. towns; cooler July afternoons than 52% of U.S. towns.
How cold does it get in Marseilles in winter?
January nights average 16°. About 139 nights a year reach 32° or below and 11 reach 0° or below. In the coldest January of the last 30 years the month averaged 15°.
How much snow does Marseilles get?
About 25 inches in a normal winter at Marseilles Lock, IL, most of it in January, with snow on the ground about 39 days a year.
How hot does it get in Marseilles?
July, with a typical high of 85° and a low of 64°. About 14 days a year reach 90° (Marseilles Lock, IL).
When is the first and last frost in Marseilles?
In half of years the last spring frost (32°) comes by April 27 and the first fall frost by October 17, about 171 frost-free days, at Marseilles Lock, IL.
What growing zone is Marseilles in?
Zone 5b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −11°.
What is the best time of year to visit Marseilles?
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 Marseilles getting warmer?
Yes: 1991–2020 averaged 1.4° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 52% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Marseilles.
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.