Frost dates for New Boston Dam 17, IL
At New Boston Dam 17, the median last spring frost (32°F) is Apr 14 and the median first fall frost is Oct 24, for a typical growing season of 190 days. For a 90% chance that the last frost has passed, wait until May 2. Nearby ZIP codes are in USDA hardiness zone 5b.
- Apr 14Last spring frost (median)50% chance of 32°F after this date
- May 2Safer planting date10% chance of 32°F after this date
- Oct 24First fall frost (median)50% chance of 32°F by this date
- 190 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 11 | Apr 27 | May 14 |
| 32°F | Apr 1 | Apr 14 | May 2 |
| 28°F | Mar 18 | Apr 5 | Apr 21 |
| 24°F | Mar 8 | Mar 25 | Apr 9 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 30 | Oct 14 | Oct 26 |
| 32°F | Oct 9 | Oct 24 | Nov 4 |
| 28°F | Oct 21 | Nov 1 | Nov 17 |
| 24°F | Oct 31 | Nov 12 | Nov 29 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 147 days | 168 days | 188 days |
| 32°F | 169 days | 190 days | 209 days |
| 28°F | 189 days | 210 days | 232 days |
| 24°F | 211 days | 232 days | 254 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 61272 | 5b | -15 to -10°F | 8 km |
| 52653 | 5b | -15 to -10°F | 9 km |
| 52646 | 5b | -15 to -10°F | 14 km |
| 61442 | 5b | -15 to -10°F | 15 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00116080, at 41.1925, -91.0578, elevation 167 m (548 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 122.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Aledo (26 km)
- Illinois City Dam 16 (26 km)
- Gladstone Dam 18 (35 km)
- Monmouth 4nw (40 km)
- Monmouth (45 km)
- Moline Quad City Intl Airport (54 km)
- Rock Island L&d 15 (55 km)
- Galesburg (63 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.