Frost dates in Naperville, Illinois
NOAA 1991–2020 normals for a 32 °F freeze. Low spots and the edge of town run colder than downtown.
Short answer
The average last spring frost in Naperville is April 28, and the average first fall frost is October 16, from NOAA's Lisle-Morton Arboretum station, 6 miles from the middle of Naperville. 1 year in 10 the last frost comes after May 14, and the first one by October 1. That leaves about 171 frost-free days. Naperville is in USDA planting zone 5b.
Weather stations around Naperville
The first row is the date most people in Naperville go by. The others show how far the dates move across the area.
| Station | Last spring frost | First fall frost | Frost-free |
|---|---|---|---|
| Lisle-Morton Arboretum 6 mi away, 680 ft | April 28 1 in 10 after May 14 | October 16 1 in 10 by October 1 | 171 days |
| Wheaton 3 SE 6 mi away, 680 ft | April 27 1 in 10 after May 14 | October 17 1 in 10 by October 1 | 173 days |
| Aurora 8 mi away, 660 ft | April 19 1 in 10 after May 4 | October 23 1 in 10 by October 9 | 187 days |
| Romeoville Wfo 11 mi away, 660 ft | April 20 1 in 10 after May 6 | October 22 1 in 10 by October 7 | 185 days |
| West Chicago Dupage Airport 12 mi away, 754 ft | April 25 1 in 10 after May 12 | October 19 1 in 10 by October 5 | 177 days |
Distances are from the middle of Naperville as the Census Bureau maps it. The average date is NOAA's 50% date: half of years have a later last frost, or an earlier first one. Plan by the 1-in-10 date if a freeze would cost you plants. The planting zone is the USDA 2023 zone for ZIP code 60540, at the middle of the city.
Your exact ZIP code
Naperville covers a lot of ground. For the station nearest your own street, and its planting zone, type your ZIP code.
How these dates work
Frost dates come from NOAA's 1991 to 2020 Climate Normals, which work out from each weather station's daily lows how likely the last spring freeze and the first fall freeze (32 °F) are by each date. We use the station nearest the middle of your ZIP code and show its height and distance, since a station on a hill or by a lake can differ from your yard.
The average date is the 50% date: half of years have a freeze after the spring date or before the fall one. The 1-in-10 dates are NOAA's 10% dates, the ones to plan by if a late freeze would cost you plants. Within one yard, cold air pools in low spots while walls and paving hold heat, so some corners freeze before others.
More frost dates
All of Illinois, station by station.
Where the numbers come from
- USDA Plant Hardiness Zone Map, 2023. Agricultural Research Service, U.S. Department of Agriculture
- PRISM Climate Group, Oregon State University (zone data)
- NOAA NCEI, U.S. Climate Normals 1991–2020, annual/seasonal
- NOAA, Normals calculation methodology (frost-freeze probability dates)
- US Census Bureau, 2025 ZCTA gazetteer (ZIP code centers)
- US Census Bureau, 2025 city population estimates and place gazetteer