Frost dates for 99812Juneau, AK
The average last spring frost in Juneau is May 4 and the average first fall frost is October 3, giving a typical growing season of about 150 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 4
- Average first fall frost
- Oct 3
- Growing season
- 150 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 18 (1-in-10 risk)
Last frost typically in 189 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 7 · May 21 · Jun 3 | Sep 6 · Sep 20 · Oct 5 | 120 days | 100% |
| Frost / freeze (32°F) | Apr 23 · May 4 · May 18 | Sep 18 · Oct 3 · Oct 20 | 150 days | 100% |
| Hard freeze (28°F) | Apr 6 · Apr 19 · May 2 | Oct 2 · Oct 18 · Nov 6 | 181 days | 100% |
Planting calendar for Juneau
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 3 – Jun 9 |
| Tomatoes | Transplant outdoors | May 20 – Jun 13 |
| Peppers | Start seeds indoors | Apr 3 – May 4 |
| Peppers | Transplant outdoors | Jun 3 – Jul 4 |
| Eggplant | Start seeds indoors | Apr 20 – May 19 |
| Eggplant | Transplant outdoors | Jun 3 – Jul 4 |
| Cucumbers | Sow outdoors | Jun 3 – Jun 23 |
| Summer squash | Sow outdoors | May 20 – Jul 4 |
| Winter squash & pumpkins | Sow outdoors | Jun 3 – Jul 4 |
| Snap beans | Sow outdoors | May 20 – Jul 16 |
| Sweet corn | Sow outdoors | May 20 – Jun 13 |
| Watermelon & cantaloupe | Sow outdoors | Jun 3 – Jul 4 |
| Okra | Sow outdoors | May 27 – Jun 19 |
| Peas | Sow outdoors (spring) | Apr 3 – May 19 |
| Potatoes | Plant outdoors (spring) | Apr 3 – Jun 3 |
| Onions | Start seeds indoors (spring) | Feb 20 – Mar 19 |
| Onions | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (spring) | Mar 16 – Apr 19 |
| Broccoli | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (fall) | Jun 3 – Jun 13 |
| Broccoli | Transplant outdoors (fall) | Jul 3 – Jul 14 |
| Cabbage | Start seeds indoors (spring) | Mar 6 – Apr 3 |
| Cabbage | Transplant outdoors (spring) | Apr 3 – May 4 |
| Cabbage | Start seeds indoors (fall) | May 24 – Jun 23 |
| Cabbage | Transplant outdoors (fall) | Jun 23 – Jul 24 |
| Leaf lettuce | Sow outdoors (spring) | Apr 3 – Jun 19 |
| Leaf lettuce | Sow outdoors (fall) | Jun 23 – Aug 9 |
| Spinach | Sow outdoors (spring) | Mar 27 – May 10 |
| Spinach | Sow outdoors (fall) | Jul 10 – Aug 14 |
| Radishes | Sow outdoors (spring) | Apr 3 – May 24 |
| Radishes | Sow outdoors (fall) | Jun 23 – Aug 24 |
| Kale | Sow outdoors (spring) | Apr 20 – May 10 |
| Kale | Sow outdoors (fall) | Jun 16 – Jul 24 |
| Carrots | Sow outdoors (spring) | May 4 – Jun 19 |
| Carrots | Sow outdoors (fall) | May 24 – Jul 9 |
| Garlic | Plant outdoors (fall) | Sep 23 – Oct 24 |
Where these dates come from
ZIP code 99812 is matched to the NOAA station Juneau Intl Ap, AK, 6.2 km away, at 16 ft elevation (6 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Juneau Intl Ap, AK (used) | 16 ft | May 4 | Oct 3 |
| Juneau Dwtn, AK | 50 ft | Apr 20 | Oct 22 |
| Eaglecrest Base, AK | 1,134 ft | May 21 | Oct 1 |
| Juneau Forecast Office, AK | 106 ft | May 9 | Oct 4 |
Frost dates near Juneau
- Juneau, AK 99802 · last Apr 20, first Oct 22
- Douglas, AK 99824 · last Apr 20, first Oct 22
- Auke Bay, AK 99821 · last May 21, first Oct 1
- Hoonah, AK 99829 · last May 9, first Oct 4
- Tenakee Springs, AK 99841 · last May 9, first Oct 4
- Gustavus, AK 99826 · last May 30, first Sep 16
- Angoon, AK 99820 · last Apr 29, first Oct 25
- Haines, AK 99827 · last Apr 25, first Oct 12
Frequently asked questions
- When is the last frost in Juneau, AK?
- For ZIP code 99812, the average last spring frost (32°F) is May 4, based on NOAA 1991-2020 climate normals for the Juneau Intl Ap, AK weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Juneau, AK?
- The average first fall frost (32°F) is October 3. There is a 1-in-10 chance of frost by September 18, so tender plants are at risk from that point on.
- How long is the growing season in 99812?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 150 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.