Frost dates for Mud Mountain Dam, WA
At Mud Mountain Dam, the median last spring frost (32°F) is Apr 18 and the median first fall frost is Oct 31, for a typical growing season of 196 days. For a 90% chance that the last frost has passed, wait until May 10. Nearby ZIP codes are in USDA hardiness zones 8a to 8b.
- Apr 18Last spring frost (median)50% chance of 32°F after this date
- May 10Safer planting date10% chance of 32°F after this date
- Oct 31First fall frost (median)50% chance of 32°F by this date
- 196 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 21 | May 6 | May 26 |
| 32°F | Mar 28 | Apr 18 | May 10 |
| 28°F | Feb 13 | Mar 15 | Apr 11 |
| 24°F | Dec 29 | Feb 11 | Mar 3 |
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 26 | Oct 12 | Nov 1 |
| 32°F | Oct 8 | Oct 31 | Nov 21 |
| 28°F | Oct 30 | Nov 17 | Dec 11 |
| 24°F | Nov 11 | Dec 3 | Jan 18 |
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 | 129 days | 157 days | 182 days |
| 32°F | 166 days | 196 days | 222 days |
| 28°F | 214 days | 247 days | 284 days |
| 24°F | 265 days | 306 days | 346 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 96% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 98396 | 8b | 15 to 20°F | 6 km |
| 98323 | 8b | 15 to 20°F | 18 km |
| 98022 | 8a | 10 to 15°F | 19 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 USC00455704, at 47.1414, -121.9356, elevation 399 m (1,308 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 79.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Buckley 1 NE (6 km)
- Palmer 3 ESE (19 km)
- McMillin Rsvr (24 km)
- Landsburg (26 km)
- Cedar Lake (33 km)
- Tacoma #1 (38 km)
- Kent (38 km)
- Rainier Paradise Ranger Station (42 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.