Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Zone 6a

In USDA zone 6a the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C). 5,187 ZIP codes (12.8% of all) are in this zone.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
ZIP codes5,187
Typical last frostApr 29
Typical first frostOct 16

Frost dates vary within zone 6a

For the middle half of zone-6a ZIP codes the last spring frost falls between Apr 22 and May 4, and the first fall frost between Oct 10 and Oct 21. The zone measures winter cold, not season length: humid Eastern and dry Western towns in the same zone can be weeks apart. Use your ZIP code for a planting date.

States with zone 6a

Illinois646 ZIPsMichigan640 ZIPsIndiana567 ZIPsOhio544 ZIPsPennsylvania510 ZIPsNew York499 ZIPsColorado274 ZIPsMissouri216 ZIPsNebraska206 ZIPsKansas178 ZIPsMassachusetts154 ZIPsNew Hampshire119 ZIPsMaine109 ZIPsUtah108 ZIPsNew Mexico64 ZIPs

Cities mostly in zone 6a

Chicago, IL80 ZIPsDenver, CO59 ZIPsColorado Springs, CO51 ZIPsAlbany, NY48 ZIPsOmaha, NE45 ZIPsFort Wayne, IN43 ZIPsMilwaukee, WI39 ZIPsSpringfield, IL35 ZIPsSyracuse, NY28 ZIPsPeoria, IL28 ZIPsLincoln, NE27 ZIPsGrand Rapids, MI26 ZIPs

← Zone 5b (colder)Zone 6b (warmer) →

Questions

What is the temperature range of zone 6a?

Zone 6a covers places where the coldest night of an average winter (the annual extreme minimum averaged over 1991–2020) is −10 to −5 °F, or −23.3 to −20.6 °C.

When is the last frost in zone 6a?

Across ZIP codes in zone 6a, the median last spring frost falls between Apr 22 and May 4 for the middle half of places. Zone alone doesn't set the frost date — check your ZIP code.

Which states have zone 6a?

Zone 6a occurs in 30 states; the most ZIP codes are in Illinois, Michigan, Indiana, Ohio, Pennsylvania.

What can I grow in zone 6a?

Perennials, shrubs and trees labeled hardy to zone 6a or a lower (colder) number should survive a typical winter. Annual vegetables depend on frost dates rather than zone.

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.