Frost dates for Ephrata Muni Airport, WA
At Ephrata Muni Airport, the median last spring frost (32°F) is Apr 22 and the median first fall frost is Oct 17, for a typical growing season of 175 days. For a 90% chance that the last frost has passed, wait until May 6. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- Apr 22Last spring frost (median)50% chance of 32°F after this date
- May 6Safer planting date10% chance of 32°F after this date
- Oct 17First fall frost (median)50% chance of 32°F by this date
- 175 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 22 | May 4 | May 22 |
| 32°F | Apr 8 | Apr 22 | May 6 |
| 28°F | Mar 19 | Apr 6 | Apr 25 |
| 24°F | Feb 26 | Mar 15 | Apr 7 |
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 22 | Oct 5 | Oct 17 |
| 32°F | Oct 3 | Oct 17 | Oct 28 |
| 28°F | Oct 14 | Oct 27 | Nov 10 |
| 24°F | Oct 24 | Nov 6 | Nov 23 |
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 | 132 days | 153 days | 171 days |
| 32°F | 156 days | 175 days | 196 days |
| 28°F | 181 days | 202 days | 225 days |
| 24°F | 206 days | 233 days | 259 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 |
|---|---|---|---|
| 98823 | 6b | -5 to 0°F | 10 km |
| 98851 | 7a | 0 to 5°F | 13 km |
| 98853 | 6b | -5 to 0°F | 25 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 USW00024141, at 47.3078, -119.5153, elevation 382 m (1,252 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 121.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Moses Lake Grant Co Airport (19 km)
- Quincy (27 km)
- Hartline (52 km)
- Wenatchee Pangborn Airport (53 km)
- Smyrna (54 km)
- Waterville (57 km)
- Wenatchee (61 km)
- Odessa (62 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.