Frost Dates: First and last frost dates for Headworks Portland Wtr, OR
ℹ️ How to read these charts for the spring
As spring unfolds, the risk of frost gradually decreases each day until your tender plants are finally safe. The probabilities shown in the chart help you make smart decisions about when to plant.
While frost typically forms at 32°F, tender plants can be damaged even when temperatures are slightly higher. Air temperatures are often measured several feet above the ground, but temperatures at plant level can be several degrees colder. Protected areas like porches help by blocking radiational cooling. Given these variables, we consider 36°F the "caution zone" for frost-sensitive plants.
Key dates for your spring planting:
- By May 1, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
- Around April 16, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
- Before April 6, there's still an 80% risk of frost — too early for tomatoes and other tender plants unless you're prepared to protect them
If the 10-day forecast shows no temperatures below 40°F, you might safely plant earlier than the above dates suggest. Many gardeners watch for this weather window to get a head start on the growing season.
| Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| Last 16° | Jan 31 | Jan 15 | Dec 30 | Dec 7 | -- | -- | -- | -- | -- |
| Last 20° | Feb 11 | Jan 28 | Jan 17 | Jan 7 | Dec 25 | Dec 4 | -- | -- | -- |
| Last 24° | Feb 22 | Feb 13 | Feb 5 | Jan 30 | Jan 24 | Jan 17 | Jan 9 | Dec 28 | -- |
| Last 28° | Mar 16 | Mar 6 | Feb 27 | Feb 21 | Feb 15 | Feb 10 | Feb 4 | Jan 28 | Jan 18 |
| Last 32° | Apr 15 | Apr 7 | Apr 1 | Mar 27 | Mar 23 | Mar 18 | Mar 13 | Mar 7 | Feb 27 |
| Last 36° | May 1 | Apr 26 | Apr 22 | Apr 19 | Apr 16 | Apr 13 | Apr 9 | Apr 6 | Mar 31 |
ℹ️ How to read these charts for the fall
As summer ends in Headworks Portland Wtr, OR, nighttime temperatures begin to drop, and your risk of frost increases with each passing day. Knowing when to expect frost helps you harvest sensitive crops and extend your growing season with protection methods.
The chart below shows the probability of experiencing specific temperatures on various dates. Here's what this means for your garden:
These probabilities help you time your end-of-season harvests and know when to apply protective measures like row covers, cloches, or cold frames to extend your harvest.
| Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| First 16° | Dec 19 | Jan 5 | Jan 20 | Feb 13 | -- | -- | -- | -- | -- |
| First 20° | Dec 5 | Dec 21 | Jan 2 | Jan 15 | Jan 30 | -- | -- | -- | -- |
| First 24° | Nov 22 | Dec 4 | Dec 13 | Dec 21 | Dec 29 | Jan 6 | Jan 15 | Jan 30 | -- |
| First 28° | Nov 6 | Nov 15 | Nov 21 | Nov 26 | Dec 1 | Dec 6 | Dec 11 | Dec 17 | Dec 26 |
| First 32° | Oct 24 | Oct 31 | Nov 6 | Nov 10 | Nov 15 | Nov 19 | Nov 23 | Nov 29 | Dec 6 |
| First 36° | Oct 12 | Oct 18 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 7 | Nov 13 |
📍 Frost Dates for other nearby locations
- Vancouver, WA 11.4 mi
- Oregon City, OR 12.2 mi
- N Willamette, OR 17.0 mi
- Troutdale, OR 20.2 mi
- Battle Ground, WA 20.5 mi
- Hillsboro, OR 21.5 mi
- Forest Grove, OR 29.4 mi
- Estacada, OR 30.2 mi
- Skamania Fish Hatchry, WA 32.8 mi
- Silverton, OR 35.9 mi
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Data is provided by the NOAA National Centers for Environmental Information.