Frost dates for 97370Philomath, OR
The average last spring frost in Philomath is May 15 and the average first fall frost is October 8, giving a typical growing season of about 145 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 15
- Average first fall frost
- Oct 8
- Growing season
- 145 days
Safer after Jun 2 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 195 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 21 · Jun 8 · Jun 26 | Sep 3 · Sep 19 · Oct 5 | 102 days | 100% |
| Frost / freeze (32°F) | Apr 28 · May 15 · Jun 2 | Sep 24 · Oct 8 · Oct 26 | 145 days | 100% |
| Hard freeze (28°F) | Apr 2 · Apr 25 · May 10 | Oct 9 · Oct 28 · Nov 13 | 186 days | 100% |
Planting calendar for Philomath
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 14 – Jun 20 |
| Tomatoes | Transplant outdoors | May 31 – Jun 18 |
| Peppers | Start seeds indoors | Apr 14 – May 15 |
| Peppers | Transplant outdoors | Jun 14 – Jul 15 |
| Eggplant | Start seeds indoors | May 1 – May 30 |
| Eggplant | Transplant outdoors | Jun 14 – Jul 15 |
| Cucumbers | Sow outdoors | Jun 14 – Jun 28 |
| Summer squash | Sow outdoors | May 31 – Jul 15 |
| Winter squash & pumpkins | Sow outdoors | Jun 14 – Jul 15 |
| Snap beans | Sow outdoors | May 31 – Jul 21 |
| Sweet corn | Sow outdoors | May 31 – Jun 18 |
| Watermelon & cantaloupe | Sow outdoors | Jun 14 – Jul 15 |
| Okra | Sow outdoors | Jun 7 – Jun 30 |
| Peas | Sow outdoors (spring) | Apr 14 – May 30 |
| Potatoes | Plant outdoors (spring) | Apr 14 – Jun 14 |
| Onions | Start seeds indoors (spring) | Mar 3 – Mar 30 |
| Onions | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (spring) | Mar 27 – Apr 30 |
| Broccoli | Transplant outdoors (spring) | May 1 – May 30 |
| Broccoli | Start seeds indoors (fall) | Jun 8 – Jun 18 |
| Broccoli | Transplant outdoors (fall) | Jul 8 – Jul 19 |
| Cabbage | Start seeds indoors (spring) | Mar 17 – Apr 14 |
| Cabbage | Transplant outdoors (spring) | Apr 14 – May 15 |
| Cabbage | Start seeds indoors (fall) | May 29 – Jun 28 |
| Cabbage | Transplant outdoors (fall) | Jun 28 – Jul 29 |
| Leaf lettuce | Sow outdoors (spring) | Apr 14 – Jun 30 |
| Leaf lettuce | Sow outdoors (fall) | Jun 28 – Aug 14 |
| Spinach | Sow outdoors (spring) | Apr 7 – May 21 |
| Spinach | Sow outdoors (fall) | Jul 15 – Aug 19 |
| Radishes | Sow outdoors (spring) | Apr 14 – Jun 4 |
| Radishes | Sow outdoors (fall) | Jun 28 – Aug 29 |
| Kale | Sow outdoors (spring) | May 1 – May 21 |
| Kale | Sow outdoors (fall) | Jun 21 – Jul 29 |
| Carrots | Sow outdoors (spring) | May 15 – Jun 30 |
| Carrots | Sow outdoors (fall) | May 29 – Jul 14 |
| Garlic | Plant outdoors (fall) | Sep 28 – Oct 29 |
Where these dates come from
ZIP code 97370 is matched to the NOAA station Corvallis Water Bureau, OR, 6.9 km away, at 592 ft elevation (133 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Corvallis Water Bureau, OR (used) | 592 ft | May 15 | Oct 8 |
| Corvallis 10 Ssw, OR | 312 ft | Apr 11 | Oct 30 |
| Corvallis State Univ, OR | 225 ft | Apr 17 | Oct 28 |
| Falls City 2 Ssw, OR | 690 ft | Apr 18 | Nov 7 |
Frost dates near Philomath
- Corvallis, OR 97333 · last Apr 17, first Oct 28
- Blodgett, OR 97326 · last May 15, first Oct 8
- Tangent, OR 97389 · last Apr 17, first Oct 28
- Albany, OR 97321 · last Apr 17, first Oct 28
- Shedd, OR 97377 · last Apr 17, first Oct 28
- Monroe, OR 97456 · last Apr 11, first Oct 23
- Alsea, OR 97324 · last Apr 13, first Nov 3
- Halsey, OR 97348 · last Apr 17, first Oct 28
Frequently asked questions
- When is the last frost in Philomath, OR?
- For ZIP code 97370, the average last spring frost (32°F) is May 15, based on NOAA 1991-2020 climate normals for the Corvallis Water Bureau, OR weather station. There is a 1-in-10 chance of a frost after June 2.
- When is the first frost in Philomath, OR?
- The average first fall frost (32°F) is October 8. There is a 1-in-10 chance of frost by September 24, so tender plants are at risk from that point on.
- How long is the growing season in 97370?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 145 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.