Frost dates for Monroe, WA
At Monroe, the median last spring frost (32°F) is Apr 17 and the median first fall frost is Oct 23, for a typical growing season of 188 days. For a 90% chance that the last frost has passed, wait until May 7. Nearby ZIP codes are in USDA hardiness zone 8b.
- Apr 17Last spring frost (median)50% chance of 32°F after this date
- May 7Safer planting date10% chance of 32°F after this date
- Oct 23First fall frost (median)50% chance of 32°F by this date
- 188 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 20 | May 5 | May 20 |
| 32°F | Mar 29 | Apr 17 | May 7 |
| 28°F | Mar 6 | Mar 26 | Apr 14 |
| 24°F | Jan 31 | Feb 28 | Mar 22 |
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 21 | Oct 6 | Oct 25 |
| 32°F | Oct 7 | Oct 23 | Nov 9 |
| 28°F | Oct 20 | Nov 8 | Nov 26 |
| 24°F | Nov 1 | Nov 23 | Dec 22 |
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 | 176 days |
| 32°F | 163 days | 188 days | 212 days |
| 28°F | 197 days | 225 days | 253 days |
| 24°F | 235 days | 268 days | 310 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 |
|---|---|---|---|
| 98296 | 8b | 15 to 20°F | 8 km |
| 98272 | 8b | 15 to 20°F | 8 km |
| 98077 | 8b | 15 to 20°F | 11 km |
| 98290 | 8b | 15 to 20°F | 12 km |
| 98019 | 8b | 15 to 20°F | 13 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 USC00455525, at 47.8453, -121.9944, elevation 37 m (120 ft).
- Data quality: Representative (10+ years), 25 years of freeze data.
- Average days per year at or below 32°F: 60.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Startup 1 E (21 km)
- Everett (21 km)
- Everett Snohomish Airport (22 km)
- Seattle Sand Point Wsfo (26 km)
- Tolt S Fk Rsvr (28 km)
- Snoqualmie Falls (36 km)
- Baring (39 km)
- Arlington (41 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.