USDA Hardiness Zone 5a
Frost Dates for 99506 — Jber, Alaska
Averages from Anchorage Merrill Fld, Ak US, the nearest reporting station, 2.7 miles away.
Plant tender crops after May 1, and expect the first autumn freeze around September 29. That leaves about 150 frost-free days.
- Last spring frost
- May 1
- First fall frost
- September 29
- Growing season
- 150 days
- Hardiness zone
- 5a
50% probability
50% probability
frost-free
-20 to -15°F annual low
- First snow
- October 22
- Last snow
- March 30
- Winters with snow
- 100%
- Snow per year
- 59.4"
median, 1991–2020
median, 1991–2020
25 of 25 observed
NOAA normal
When it snows in Jber, Alaska
The first measurable snow (0.1 inch or more) in Jber, Alaska usually arrives around October 22, and the last of the season around March 30. Those are the middle dates across the winters of 1991–2020 at Ft Richardson Wtp, Ak US, 4.1 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow.
For a gardener, snow matters less than frost: a light snow on frozen ground changes nothing, while a hard frost on an unprotected bed ends the season. Use the frost dates above for planting and the snow dates for getting hoses drained, mulch down and tender pots indoors.
Planting calendar for 99506
| When | What to do |
|---|---|
| February 20 – March 6 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| March 6 – March 20 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| April 3 – April 17 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| May 1 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by July 7 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by September 15 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| September 29 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after May 1 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Jber, Alaska are past their last freeze. Harvest before September 29, which leaves roughly 150 frost-free days.
ZIP 99506 sits in USDA hardiness zone 5a, meaning the average coldest night of the year falls between -20 to -15°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.