Frost dates for Pasco Tri Cities Airport, WA
At Pasco Tri Cities Airport, the median last spring frost (32°F) is Apr 27 and the median first fall frost is Oct 11, for a typical growing season of 168 days. For a 90% chance that the last frost has passed, wait until May 10. Nearby ZIP codes are in USDA hardiness zones 7a to 7b.
- Apr 27Last spring frost (median)50% chance of 32°F after this date
- May 10Safer planting date10% chance of 32°F after this date
- Oct 11First fall frost (median)50% chance of 32°F by this date
- 168 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 27 | May 9 | May 23 |
| 32°F | Apr 8 | Apr 27 | May 10 |
| 28°F | Mar 20 | Apr 7 | Apr 28 |
| 24°F | Feb 27 | Mar 19 | Apr 6 |
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 29 | Oct 13 |
| 32°F | Sep 28 | Oct 11 | Oct 27 |
| 28°F | Oct 6 | Oct 23 | Nov 8 |
| 24°F | Oct 18 | Nov 2 | Nov 26 |
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 | 124 days | 143 days | 161 days |
| 32°F | 148 days | 168 days | 189 days |
| 28°F | 173 days | 197 days | 224 days |
| 24°F | 202 days | 228 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% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99336 | 7b | 5 to 10°F | 7 km |
| 99352 | 7b | 5 to 10°F | 14 km |
| 99354 | 7b | 5 to 10°F | 16 km |
| 99338 | 7b | 5 to 10°F | 16 km |
| 99301 | 7a | 0 to 5°F | 18 km |
| 99323 | 7a | 0 to 5°F | 21 km |
| 99353 | 7b | 5 to 10°F | 21 km |
| 99337 | 7b | 5 to 10°F | 24 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 USW00024163, at 46.2667, -119.1167, elevation 124 m (407 ft).
- Data quality: Representative (10+ years), 21 years of freeze data.
- Average days per year at or below 32°F: 112.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Kennewick (6 km)
- Richland (12 km)
- Sagemoor (15 km)
- Eltopia 8 WSW (15 km)
- Ice Harbor Dam (18 km)
- McNary Dam (39 km)
- Connell 1 W (48 km)
- Prosser (50 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.