What temperature range is USDA zone 3a?

Zone 3a covers areas whose average annual extreme minimum winter temperature is −40 to −35 °F. Each numbered zone is a 10°F band; the "a" and "b" half-zones split it into 5°F steps.

Does zone 3a tell me when to plant?

No — the hardiness zone tells you which perennials survive winter, not when to sow annual vegetables. Planting dates depend on your local last and first frost, which can vary within a single zone. Open one of the sample locations in zone 3a to see its frost calendar and per-crop planting windows.

What can I grow in zone 3a?

Almost any common vegetable can be grown in zone 3a; what changes with zone and local climate is the timing and the length of the season. Cold-hardy crops (peas, spinach, lettuce) go out earliest, tender crops (tomatoes, peppers, basil) after the last frost. Use each location's calendar for exact dates.

USDA hardiness zone 3a — frost dates & what to plant

USDA hardiness zone 3a

Average annual extreme minimum temperature: −40 to −35 °F

USDA plant hardiness zone 3a covers areas whose average annual extreme minimum winter temperature is −40 to −35 °F — the standard USDA measure of which perennials survive an average winter. Hardiness zone sets winter survival, but planting DATES depend on your local frost calendar, which varies within a zone. 15 locations on this site fall in zone 3a (Arctic, AK, Big Falls, MN, Brevig Mission, AK, Coldfoot, AK, Crooked Creek, AK, Deering, AK, Dry Creek, AK, Grayling, AK, and 7 more); open one to see its frost dates, growing-season length, and a printable per-crop planting calendar.

Locations in zone 3a

Same zone, different frost calendars — open one for its full planner.
Location	Last frost	First frost	Season (days)
Arctic, AK	May 25	Aug 26	92
Big Falls, MN	May 23	Sep 21	118
Brevig Mission, AK	Jun 5	Sep 3	88
Coldfoot, AK	May 22	Aug 24	94
Crooked Creek, AK	May 13	Sep 13	120
Deering, AK	Jun 5	Sep 24	110
Dry Creek, AK	May 30	Aug 24	84
Grayling, AK	May 25	Sep 3	101
Holy Cross, AK	May 21	Sep 22	122
Lime, AK	May 12	Sep 24	134
Point Hope, AK	Jun 10	Sep 11	92
Ranier, MN	May 29	Sep 13	109
Soudan, MN	May 28	Sep 14	108
Tanana, AK	May 29	Aug 28	89
Tower, MN	May 12	Oct 1	138

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.

What zone 3a means for your garden

A plant rated "hardy to zone 3a" can be expected to survive a winter whose coldest night lands in the −40 to −35 °F range — the metric the USDA map is built on. That governs perennials, shrubs, and trees. For annual vegetables, what matters is the frost calendar: the dates of the average last spring and first fall freeze, which set when it is safe to plant and how long the season runs. Those come from the individual location pages above.

Zones are from the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP — see the methodology page. Browse all hardiness zones or crop-by-crop timing.

Frequently asked questions

What temperature range is USDA zone 3a?: Zone 3a covers areas whose average annual extreme minimum winter temperature is −40 to −35 °F. Each numbered zone is a 10°F band; the "a" and "b" half-zones split it into 5°F steps.
Does zone 3a tell me when to plant?: No — the hardiness zone tells you which perennials survive winter, not when to sow annual vegetables. Planting dates depend on your local last and first frost, which can vary within a single zone. Open one of the sample locations in zone 3a to see its frost calendar and per-crop planting windows.
What can I grow in zone 3a?: Almost any common vegetable can be grown in zone 3a; what changes with zone and local climate is the timing and the length of the season. Cold-hardy crops (peas, spinach, lettuce) go out earliest, tender crops (tomatoes, peppers, basil) after the last frost. Use each location's calendar for exact dates.