Frost dates for 99833Petersburg, AK
The average last spring frost in Petersburg is April 29 and the average first fall frost is October 17, giving a typical growing season of about 169 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 29
- Average first fall frost
- Oct 17
- Growing season
- 169 days
Safer after May 14 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 180 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) | Apr 30 · May 14 · May 29 | Sep 16 · Oct 1 · Oct 17 | 138 days | 100% |
| Frost / freeze (32°F) | Apr 15 · Apr 29 · May 14 | Sep 30 · Oct 17 · Nov 1 | 169 days | 100% |
| Hard freeze (28°F) | Mar 26 · Apr 11 · Apr 30 | Oct 14 · Nov 1 · Nov 20 | 204 days | 100% |
Planting calendar for Petersburg
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 | Mar 29 – Jun 4 |
| Tomatoes | Transplant outdoors | May 15 – Jun 27 |
| Peppers | Start seeds indoors | Mar 29 – Apr 29 |
| Peppers | Transplant outdoors | May 29 – Jun 29 |
| Eggplant | Start seeds indoors | Apr 15 – May 14 |
| Eggplant | Transplant outdoors | May 29 – Jun 29 |
| Cucumbers | Sow outdoors | May 29 – Jul 7 |
| Summer squash | Sow outdoors | May 15 – Jun 29 |
| Winter squash & pumpkins | Sow outdoors | May 29 – Jun 29 |
| Snap beans | Sow outdoors | May 15 – Jul 30 |
| Sweet corn | Sow outdoors | May 15 – Jun 27 |
| Watermelon & cantaloupe | Sow outdoors | May 29 – Jun 29 |
| Okra | Sow outdoors | May 22 – Jun 14 |
| Peas | Sow outdoors (spring) | Mar 29 – May 14 |
| Potatoes | Plant outdoors (spring) | Mar 29 – May 29 |
| Onions | Start seeds indoors (spring) | Feb 15 – Mar 14 |
| Onions | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (spring) | Mar 11 – Apr 14 |
| Broccoli | Transplant outdoors (spring) | Apr 15 – May 14 |
| Broccoli | Start seeds indoors (fall) | Jun 17 – Jun 27 |
| Broccoli | Transplant outdoors (fall) | Jul 17 – Jul 28 |
| Cabbage | Start seeds indoors (spring) | Mar 1 – Mar 29 |
| Cabbage | Transplant outdoors (spring) | Mar 29 – Apr 29 |
| Cabbage | Start seeds indoors (fall) | Jun 7 – Jul 7 |
| Cabbage | Transplant outdoors (fall) | Jul 7 – Aug 7 |
| Leaf lettuce | Sow outdoors (spring) | Mar 29 – Jun 14 |
| Leaf lettuce | Sow outdoors (fall) | Jul 7 – Aug 23 |
| Spinach | Sow outdoors (spring) | Mar 22 – May 5 |
| Spinach | Sow outdoors (fall) | Jul 24 – Aug 28 |
| Radishes | Sow outdoors (spring) | Mar 29 – May 19 |
| Radishes | Sow outdoors (fall) | Jul 7 – Sep 7 |
| Kale | Sow outdoors (spring) | Apr 15 – May 5 |
| Kale | Sow outdoors (fall) | Jun 30 – Aug 7 |
| Carrots | Sow outdoors (spring) | Apr 29 – Jun 14 |
| Carrots | Sow outdoors (fall) | Jun 7 – Jul 23 |
| Garlic | Plant outdoors (fall) | Oct 7 – Nov 7 |
Where these dates come from
ZIP code 99833 is matched to the NOAA station Petersburg 1, AK, 13.8 km away, at 107 ft elevation (1,950 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Petersburg 1, AK (used) | 107 ft | Apr 29 | Oct 17 |
| Pt Baker, AK | 20 ft | Apr 19 | Oct 25 |
| Wrangell Ap, AK | 56 ft | Apr 11 | Nov 1 |
| Little Port Walter, AK | 14 ft | Apr 21 | Oct 31 |
Frost dates near Petersburg
- Kake, AK 99830 · last Apr 29, first Oct 17
- Point Baker, AK 99927 · last Apr 19, first Oct 25
- Wrangell, AK 99929 · last Apr 11, first Nov 1
- Coffman Cove, AK 99918 · last Apr 29, first Oct 16
Frequently asked questions
- When is the last frost in Petersburg, AK?
- For ZIP code 99833, the average last spring frost (32°F) is April 29, based on NOAA 1991-2020 climate normals for the Petersburg 1, AK weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in Petersburg, AK?
- The average first fall frost (32°F) is October 17. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 99833?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 169 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.