When is the last frost in Grand Forks, ND?

The average last spring frost (50% probability of 32°F) in Grand Forks is around May 10, based on NOAA/NCEI 1991–2020 normals at the Grand Forks Univ (Nws), ND station (4.3 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Grand Forks?

The average first fall frost in Grand Forks, ND is around October 1, giving roughly a 144-day frost-free growing season.

What planting zone is Grand Forks, ND?

Grand Forks is in USDA plant hardiness zone 4a (average annual extreme minimum temperature -30 to -25°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Grand Forks?

In Grand Forks, ND the warmest month is July (avg high 80.1°F) and the coldest is January (avg low -1.3°F). It averages about 22.8″ of precipitation a year and 48.7″ of snow.

Home › North Dakota › Grand Forks

Grand Forks, ND Planting Calendar & Frost Dates

USDA hardiness zone 4a · ZIP 58201 · elevation 253′ · NOAA & USDA data

Grand Forks is in USDA hardiness zone 4a (winters can dip to -30 to -25°F), with a growing season of about 144 days between the average last spring frost (May 10) and first fall frost (October 1). The warmest month is July (avg high 80.1°F); the coldest is January (avg low -1.3°F). It averages 22.8″ of precipitation a year and 48.7″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -30 to -25°F

Last spring frost

May 10

avg (50% prob, 32°F)

First fall frost

October 1

avg (50% prob, 32°F)

Growing season

144 days

frost-free window

Warmest month

July

avg high 80.1°F

Month-by-month typical weather in Grand Forks

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Grand Forks Univ (Nws), ND (4.3 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	15.3	-1.3	7	0.5	9.5
February	20.4	2.5	11.4	0.6	8.2
March	34	16.7	25.4	0.9	7.8
April	52	31	41.5	1.2	3
May	66.5	43.5	55	3	0.1
June	75.9	54.8	65.4	4.1	0
July	80.1	58.8	69.5	3.6	0
August	79.2	56.5	67.8	3	0
September	69.7	47.4	58.5	2.4	0
October	53.3	34.5	43.9	2	1.5
November	35	19.6	27.3	0.8	5.1
December	21	5.8	13.4	0.7	13.5

What to plant when in Grand Forks

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 29 · Transplant out: May 17
Peppers	warm	Start seeds indoors: March 15 · Transplant out: May 24
Cucumbers	warm	Direct sow: May 17
Zucchini / squash	warm	Direct sow: May 17
Bush beans	warm	Direct sow: May 17
Sweet corn	warm	Direct sow: May 17
Basil	warm	Transplant out: May 17
Peas	cool	Sow (spring): April 5 · Sow (fall): August 6
Spinach	cool	Sow (spring): March 29 · Sow (fall): August 6
Lettuce	cool	Sow (spring): April 12 · Sow (fall): August 6
Kale	cool	Transplant (spring): April 19 · Sow (fall): July 23
Broccoli	cool	Transplant (spring): April 26
Carrots	cool	Sow (spring): April 19 · Sow (fall): July 23
Onions	cool	Transplant (spring): April 12
Potatoes	cool	Plant seed potatoes: April 26
Radishes	cool	Sow (spring): April 12 · Sow (fall): August 20

Dates are computed from Grand Forks's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

Want the exact dates for your yard? →
Look up your precise ZIP-code frost dates and a full 26-crop planting calendar on our free interactive tool.
Open the frost & planting tool

🌾 Get a frost reminder

One email in early spring and early fall with the dates for your area. No spam.

Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in North Dakota

Fargo, ND Bismarck, ND Minot, ND

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Grand Forks Univ (Nws), ND, 4.3 mi (confidence: high). Monthly weather normals: Grand Forks Univ (Nws), ND, 4.3 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.