Frost dates for 97865Mount Vernon, OR
The average last spring frost in Mount Vernon is May 28 and the average first fall frost is September 18, giving a typical growing season of about 113 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 28
- Average first fall frost
- Sep 18
- Growing season
- 113 days
Safer after Jun 15 (1-in-10 risk)
Possible by Sep 2 (1-in-10 risk)
Last frost typically in 208 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 31 · Jun 19 · Jul 8 | Aug 16 · Sep 2 · Sep 20 | 76 days | 100% |
| Frost / freeze (32°F) | May 12 · May 28 · Jun 15 | Sep 2 · Sep 18 · Oct 4 | 113 days | 100% |
| Hard freeze (28°F) | Apr 25 · May 8 · May 24 | Sep 13 · Oct 1 · Oct 16 | 146 days | 100% |
Planting calendar for Mount Vernon
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 27 – Jul 3 |
| Tomatoes | Transplant outdoors | Jun 13 – May 29 |
| Peppers | Start seeds indoors | Apr 27 – May 28 |
| Peppers | Transplant outdoors | Jun 27 – Jul 28 |
| Eggplant | Start seeds indoors | May 14 – Jun 12 |
| Eggplant | Transplant outdoors | Jun 27 – Jul 28 |
| Cucumbers | Sow outdoors | Jun 27 – Jun 8 |
| Summer squash | Sow outdoors | Jun 13 – Jul 28 |
| Winter squash & pumpkins | Sow outdoors | Jun 27 – Jul 28 |
| Snap beans | Sow outdoors | Jun 13 – Jul 1 |
| Sweet corn | Sow outdoors | Jun 13 – May 29 |
| Watermelon & cantaloupe | Sow outdoors | Jun 27 – Jul 28 |
| Okra | Sow outdoors | Jun 20 – Jul 13 |
| Peas | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Potatoes | Plant outdoors (spring) | Apr 27 – Jun 27 |
| Onions | Start seeds indoors (spring) | Mar 16 – Apr 12 |
| Onions | Transplant outdoors (spring) | May 14 – Jun 12 |
| Broccoli | Start seeds indoors (spring) | Apr 9 – May 13 |
| Broccoli | Transplant outdoors (spring) | May 14 – Jun 12 |
| Broccoli | Start seeds indoors (fall) | May 19 – May 29 |
| Broccoli | Transplant outdoors (fall) | Jun 18 – Jun 29 |
| Cabbage | Start seeds indoors (spring) | Mar 30 – Apr 27 |
| Cabbage | Transplant outdoors (spring) | Apr 27 – May 28 |
| Cabbage | Start seeds indoors (fall) | May 9 – Jun 8 |
| Cabbage | Transplant outdoors (fall) | Jun 8 – Jul 9 |
| Leaf lettuce | Sow outdoors (spring) | Apr 27 – Jul 13 |
| Leaf lettuce | Sow outdoors (fall) | Jun 8 – Jul 25 |
| Spinach | Sow outdoors (spring) | Apr 20 – Jun 3 |
| Spinach | Sow outdoors (fall) | Jun 25 – Jul 30 |
| Radishes | Sow outdoors (spring) | Apr 27 – Jun 17 |
| Radishes | Sow outdoors (fall) | Jun 8 – Aug 9 |
| Kale | Sow outdoors (spring) | May 14 – Jun 3 |
| Kale | Sow outdoors (fall) | Jun 1 – Jul 9 |
| Carrots | Sow outdoors (spring) | May 28 – Jul 13 |
| Carrots | Sow outdoors (fall) | May 9 – Jun 24 |
| Garlic | Plant outdoors (fall) | Sep 8 – Oct 9 |
Where these dates come from
ZIP code 97865 is matched to the NOAA station John Day, OR, 12.1 km away, at 3,063 ft elevation (202 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| John Day, OR (used) | 3,063 ft | May 28 | Sep 18 |
| Seneca, OR | 4,660 ft | — | — |
| Long Creek, OR | 3,740 ft | Jun 5 | Sep 14 |
| Dayville 8 Nw, OR | 2,260 ft | May 4 | Oct 6 |
Frost dates near Mount Vernon
- John Day, OR 97845 · last May 28, first Sep 18
- Canyon City, OR 97820 · last May 28, first Sep 18
- Seneca, OR 97873 · last —, first —
- Prairie City, OR 97869 · last May 28, first Sep 18
- Dayville, OR 97825 · last May 4, first Oct 6
- Long Creek, OR 97856 · last Jun 5, first Sep 14
- Bates, OR 97817 · last —, first —
- Monument, OR 97864 · last May 9, first Sep 27
Frequently asked questions
- When is the last frost in Mount Vernon, OR?
- For ZIP code 97865, the average last spring frost (32°F) is May 28, based on NOAA 1991-2020 climate normals for the John Day, OR weather station. There is a 1-in-10 chance of a frost after June 15.
- When is the first frost in Mount Vernon, OR?
- The average first fall frost (32°F) is September 18. There is a 1-in-10 chance of frost by September 2, so tender plants are at risk from that point on.
- How long is the growing season in 97865?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 113 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.