Frost dates for Mason City, NE
At Mason City, the median last spring frost (32°F) is May 3 and the median first fall frost is Oct 5, for a typical growing season of 153 days. For a 90% chance that the last frost has passed, wait until May 18. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 3Last spring frost (median)50% chance of 32°F after this date
- May 18Safer planting date10% chance of 32°F after this date
- Oct 5First fall frost (median)50% chance of 32°F by this date
- 153 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 30 | May 14 | May 27 |
| 32°F | Apr 21 | May 3 | May 18 |
| 28°F | Apr 10 | Apr 24 | May 8 |
| 24°F | Mar 30 | Apr 14 | Apr 30 |
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 15 | Sep 27 | Oct 9 |
| 32°F | Sep 23 | Oct 5 | Oct 16 |
| 28°F | Sep 30 | Oct 15 | Oct 26 |
| 24°F | Oct 10 | Oct 24 | Nov 5 |
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 | 118 days | 135 days | 152 days |
| 32°F | 135 days | 153 days | 172 days |
| 28°F | 151 days | 172 days | 193 days |
| 24°F | 172 days | 193 days | 211 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 |
|---|---|---|---|
| 68855 | 5b | -15 to -10°F | 6 km |
| 68814 | 5b | -15 to -10°F | 14 km |
| 68852 | 5b | -15 to -10°F | 14 km |
| 68858 | 5b | -15 to -10°F | 29 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 USC00255250, at 41.2211, -99.2939, elevation 699 m (2,292 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 166.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Loup City (28 km)
- Broken Bow Muni Airport (37 km)
- Ravenna (38 km)
- Comstock (38 km)
- Broken Bow 2 W (38 km)
- Oconto (40 km)
- Ord Evelyn Sharp Field (53 km)
- N Loup (53 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.