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What Hardiness Zone Is New Hampshire?

USDA 2023 Plant Hardiness Zone Map · 280 ZIP codes · Data updated 2026-10-28

Quick answer

New Hampshire spans USDA hardiness zones 4a–6b on the 2023 Plant Hardiness Zone Map. The most common zone is 6a, covering 43% of New Hampshire's ZIP codes, followed by zone 5b (30%). Zone 6a means the coldest night of an average winter reaches −10°F to −5°F (−23°C to −21°C). Enter your ZIP code for your exact zone.

New Hampshire hardiness zones by share of ZIP codes

Zone 4a2% · 5 ZIPs
Zone 4b4% · 10 ZIPs
Zone 5a21% · 59 ZIPs
Zone 5b30% · 85 ZIPs
Zone 6a43% · 119 ZIPs
Zone 6b<1% · 2 ZIPs

What the zones mean for New Hampshire gardeners

  • Coldest and warmest towns: among towns with NOAA weather stations, First Connecticut Lake (1,650 ft) is in zone 4a, while Durham 2 SSW (63 ft) is in zone 6a. That is a difference of about 20°F in the coldest night of a typical winter.
  • Same zone, different frost dates: within zone 6a, the median last spring frost ranges from April 21 at Manchester Airport to May 10 at Greenville 1 NNE, 19 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.

Typical frost dates in each New Hampshire zone

Medians across NOAA weather stations in each zone. Colder zones usually have later spring frosts, but local terrain can shift the dates by weeks.

ZoneLast spring frostFirst fall frostStations
4aMay 25September 243
4bMay 21September 266
5aMay 14October 114
5bMay 8October 312
6aMay 3October 816

Hardiness zones for New Hampshire cities

Zones at the National Weather Service stations, mostly city airports, with their median frost dates.
Berlin Municipal Airport4b−25°F to −20°F1,158May 30Sep 19
Concord Municipal Airport5b−15°F to −10°F346May 8Oct 3
Durham 2 N6a−10°F to −5°F119May 3Oct 10
Durham 2 SSW6a−10°F to −5°F63May 7Oct 4
Jaffrey Municipal Airport5b−15°F to −10°F1,040May 5Oct 6
Lebanon Municipal Airport5a−20°F to −15°F598May 9Oct 6
Manchester Airport6a−10°F to −5°F225Apr 21Oct 19
Mount Washington5a−20°F to −15°F6,267Any monthAny month
Rochester Skyhaven Airport6a−10°F to −5°F323Apr 30Oct 9
Whitefield Mount Washington Airport4b−25°F to −20°F1,074May 27Sep 19

Hardiness zones for 52 towns in New Hampshire

Each NOAA weather station is shown with the USDA zone of the nearest ZIP code (within 8 miles). Coldest night is the zone's range for the average annual extreme minimum temperature. Click a column to sort.
Benton 5 SW5a−20°F to −15°F1,200May 15Sep 28
Berlin4b−25°F to −20°F920May 14Sep 30
Berlin Municipal Airport4b−25°F to −20°F1,158May 30Sep 19
Bethlehem 25a−20°F to −15°F1,180May 24Sep 18
Bradford 25b−15°F to −10°F815May 15Sep 27
Colebrook 3SW4a−30°F to −25°F1,120May 31Sep 21
Concord Municipal Airport5b−15°F to −10°F346May 8Oct 3
Durham 2 N6a−10°F to −5°F119May 3Oct 10
Durham 2 SSW6a−10°F to −5°F63May 7Oct 4
E Milford6a−10°F to −5°F240Apr 28Oct 8
E Sandwich5a−20°F to −15°F692May 6Oct 6
Epping6a−10°F to −5°F160May 7Oct 4
First Connecticut Lake4a−30°F to −25°F1,650May 25Sep 24
Franklin Falls Dam5b−15°F to −10°F450May 7Oct 3
Gorham Airport5a−20°F to −15°F800May 14Sep 26
Grafton5a−20°F to −15°F830May 21Sep 26
Greenland6a−10°F to −5°F95May 4Oct 8
Greenville 1 NNE6a−10°F to −5°F900May 10Oct 6
Hanover5a−20°F to −15°F584May 1Oct 13
Hopkinton Lake5b−15°F to −10°F430May 6Oct 1
Hudson 1 SSE6a−10°F to −5°F185May 3Oct 8
Jaffrey Municipal Airport5b−15°F to −10°F1,040May 5Oct 6
Jaffrey Silver Rch Airpark6a−10°F to −5°F1,030May 5Oct 6
Jefferson4b−25°F to −20°F1,235May 8Oct 1
Keene5b−15°F to −10°F511May 14Oct 1
Lakeport 25b−15°F to −10°F500Apr 30Oct 18
Lancaster4b−25°F to −20°F860May 18Sep 30
Lebanon Municipal Airport5a−20°F to −15°F598May 9Oct 6
Lincoln Nepp5a−20°F to −15°F807May 7Oct 4
Manchester Airport6a−10°F to −5°F225Apr 21Oct 19
Massabesic Lake6a−10°F to −5°F253Apr 30Oct 11
Meredith 3 NNE5b−15°F to −10°F861Apr 28Oct 16
Milford6a−10°F to −5°F320May 3Oct 5
Mount Sunapee5b−15°F to −10°F1,275May 2Oct 9
Mount Washington5a−20°F to −15°F6,267Any monthAny month
N Conway5a−20°F to −15°F522May 7Oct 5
N Stratford4a−30°F to −25°F950May 19Sep 29
Nashua 2 NNW6a−10°F to −5°F135Apr 30Oct 12
Nashua Cwsu6a−10°F to −5°F180Apr 29Oct 8
Newport5a−20°F to −15°F770May 14Oct 1
Pinkham Notch5a−20°F to −15°F2,025May 18Oct 1
Plymouth5b−15°F to −10°F660May 20Sep 27
Rochester Skyhaven Airport6a−10°F to −5°F323Apr 30Oct 9
Salisbury5b−15°F to −10°F550May 14Sep 29
Tamworth 45a−20°F to −15°F541May 16Sep 26
W Hampstead6a−10°F to −5°F288Apr 30Oct 11
Walpole 2S Nepp5b−15°F to −10°F604May 8Oct 3
Waterville Valley Nepp5a−20°F to −15°F1,429May 15Sep 28
Weare6a−10°F to −5°F720May 2Oct 8
Wentworth5a−20°F to −15°F653May 12Oct 6
Whitefield Mount Washington Airport4b−25°F to −20°F1,074May 27Sep 19
York Pond4b−25°F to −20°F1,519May 23Sep 22

Frequently asked questions

What hardiness zone is New Hampshire?

New Hampshire is in USDA hardiness zones 4a–6b on the 2023 USDA Plant Hardiness Zone Map. Zone 6a is the most common, covering 43% of New Hampshire's ZIP codes, and zone 5b covers 30%. Enter your ZIP code for your exact zone.

What does zone 6a mean?

Zone 6a means the average annual extreme minimum temperature, the coldest night of a typical winter, is −10°F to −5°F (−23°C to −21°C). Perennials, shrubs and trees rated for zone 6a or colder should survive winter there.

What is the coldest hardiness zone in New Hampshire?

Zone 4a is the coldest zone mapped in New Hampshire, found around First Connecticut Lake, and zone 6b is the warmest.

Did New Hampshire's hardiness zones change in 2023?

The USDA released a new Plant Hardiness Zone Map in November 2023, based on 1991–2020 temperatures instead of 1976–2005. About half of the United States shifted half a zone warmer. Check your ZIP code here, because plant tags and older books may still list your 2012 zone.

When should I plant in zone 6a?

Hardiness zones don't set planting dates; frost dates do. Inside zone 6a in New Hampshire, the median last spring frost varies from April 21 to May 10. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.

Zone and frost dates: use both

Your hardiness zone answers one question: will this plant survive the winter here? Choose perennials, shrubs, trees and bulbs rated for your zone or a colder one. For vegetables and annuals, what matters is the length of the frost-free season. See New Hampshire frost dates by town, or get a planting calendar for your ZIP code with start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Zones are from the USDA 2023 Plant Hardiness Zone Map ZIP-code files published by the PRISM Climate Group, Oregon State University, based on 1991–2020 minimum temperatures. ZIP codes are assigned to states by USPS prefix. Town zones use the ZIP code nearest each NOAA 1991–2020 Climate Normals station. This is an independent tool, not an official USDA site. Full methodology.

Hardiness zones in other states