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

Planting zone for 03593 — Randolph, NH

ZIP code 03593 (Randolph, Coos County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 18 and the first fall frost October 1.

Where ZIP 03593 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

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.

Zone5a−20 to −15 °F
Coldest night−28.9 to −26.1 °C
Last frostMay 18
First frostOct 1
2012 zone4b

Was 4b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Randolph, NH…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Randolph, NH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 18median — 50% chance of a later frost
Safe for tender plantsJune 1only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 15
Growing season135 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 4 and returns around October 12.

From the NOAA station Pinkham Notch, NH — 4 miles away, elevation 2,024 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 03593

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 6 – Apr 20
SpinachSow outdoors · Apr 6 – Apr 27
Broccoli, cabbageStart indoors · Mar 9 – Mar 23
Broccoli, cabbageTransplant · Apr 27 – May 11
Onion setsPlant outdoors · Apr 20 – May 4
PotatoesPlant outdoors · Apr 27 – May 11
LettuceSow outdoors · Apr 20 – May 4
Carrots, beetsSow outdoors · Apr 27 – May 11
TomatoesStart indoors · Mar 23 – Apr 6
TomatoesTransplant · May 25 – Jun 8
Peppers, eggplantStart indoors · Mar 9 – Mar 23
Peppers, eggplantTransplant · Jun 1 – Jun 15
BeansSow outdoors · May 25 – Jun 8
Sweet cornSow outdoors · May 25 – Jun 8
Cucumbers, squashSow outdoors · May 25 – Jun 8
Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20
GarlicPlant cloves · Sep 17 – Oct 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 18) and first fall frost (Oct 1) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 03593 came on May 16 — 3 days earlier than the 1991–2020 average (May 19).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Randolph, NH

The center of ZIP 03593 is mapped as No Digital Data Available: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 03593; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Randolph, NH

Summer high55 °Faverage high, July
Winter low−3 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights233nights a year at 32 °F or less
Growing degree days181base 50 °F — the season’s usable heat
Longest day15 h 32 mindaylight on June 21
Shortest day8 h 51 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation91.2 inper year, rain and melted snow
Snowfall282 inper year; 191 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°32 °FJanuary: average high 15 °F, low -3 °F 15°−3° JanFebruary: average high 15 °F, low -3 °F 15°−3° FebMarch: average high 21 °F, low 5 °F 21°5° MarApril: average high 31 °F, low 17 °F 31°17° AprMay: average high 43 °F, low 30 °F 43°30° MayJune: average high 51 °F, low 40 °F 51°40° JunJuly: average high 55 °F, low 45 °F 55°45° JulAugust: average high 54 °F, low 43 °F 54°43° AugSeptember: average high 49 °F, low 37 °F 49°37° SepOctober: average high 38 °F, low 25 °F 38°25° OctNovember: average high 28 °F, low 13 °F 28°13° NovDecember: average high 20 °F, low 4 °F 20°4° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″8″10″January: 5.74 in precipitation, 41.4 in snowfall 5.7❄41 JanFebruary: 5.45 in precipitation, 43.3 in snowfall 5.5❄43 FebMarch: 6.72 in precipitation, 46.2 in snowfall 6.7❄46 MarApril: 7.31 in precipitation, 33.1 in snowfall 7.3❄33 AprMay: 7.68 in precipitation, 12.9 in snowfall 7.7❄13 MayJune: 8.59 in precipitation, 1.3 in snowfall 8.6❄1 JunJuly: 8.93 in precipitation 8.9 JulAugust: 7.72 in precipitation, 0.1 in snowfall 7.7 AugSeptember: 7.66 in precipitation, 1.2 in snowfall 7.7❄1 SepOctober: 9.99 in precipitation, 19 in snowfall 10.0❄19 OctNovember: 8.09 in precipitation, 35.6 in snowfall 8.1❄36 NovDecember: 7.35 in precipitation, 47.7 in snowfall 7.3❄48 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Washington, NH (2 mi away); precipitation: Mt Washington, NH (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

035755a
Bretton Woods, NH · 5 mi
035954b
Twin Mountain, NH · 10 mi
035834b
Jefferson, NH · 10 mi
038465a
Jackson, NH · 11 mi
035815a
Gorham, NH · 11 mi
038385a
Glen, NH · 14 mi
038125a
Bartlett, NH · 15 mi
035704b
Berlin, NH · 15 mi

New Hampshire planting zones →

Questions about 03593

What planting zone is ZIP code 03593?

ZIP code 03593 (Randolph, NH) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Randolph, NH?

The median last spring frost (32 °F) near 03593 is May 18; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pinkham Notch station.

When is the first frost in Randolph, NH?

The median first fall frost near 03593 is October 1, giving a median frost-free growing season of 135 days.

When should I plant tomatoes in 03593?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 03593 get?

About 91.2 inches of precipitation a year and 282 inches of snowfall (NOAA 1991–2020 normals, Mt Washington station).

How hot do summers get in Randolph, NH?

The average high peaks at 55 °F in July, with about 0 days a year at 90 °F or more.

Did spring come early in Randolph, NH in 2026?

Spring leaf-out near 03593 came on May 16 in 2026, 3 days earlier than the 1991–2020 average (May 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Randolph, NH?

Long-day onions: the longest day near 03593 is 15 h 32 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 03593 change?

Yes. The 2012 USDA map put 03593 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.