Last and first frost dates in Grand Forks

When is the last frost in Grand Forks?

The last frost in Grand Forks usually comes around 10 May: that is the median of 2016–2025, so in about half of those years the last night at or below 0 °C came later. Hardy crops start before it and frost-tender ones only after it: in the table below arugula can go into open ground from 19 April, while corn waits until 17 May. The first autumn frost follows around 16 October, about 159 days later: harvest or cover frost-tender crops before then.

When to sow and plant

Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

When the soil warms up in Grand Forks

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo). The soil reaches 10 °C 3 days before the last spring frost and 15 °C 14 days after it.

Frost dates near Grand Forks

Of the nearest cities on our list, the last spring frost ends earliest in Duluth (28 April) and latest in Winnipeg (12 May).

Seeds, seedlings and markets in Grand Forks

Within 15 km of Grand Forks OpenStreetMap lists 2 markets (collected 29 October 2026). The nearest market to the city centre is Town Square Farmers Market, 5 km away.

• Town Square Farmers Market — market
  Jun 17–Sept 30 Sat 09:00–13:00 · 5 km · tsfarmersmarket.com

• Where to buy seeds and seedlings in Grand Forks
• Selling your own harvest in the United States

Places: © OpenStreetMap contributors, ODbL.

Weather in Grand Forks by month

Average weather in Grand Forks over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: May–September (20.5–27.9 °C). Nights average below 0 °C in November–April (-15.9–-0.8 °C). About 599 mm of rain falls in a year, on 92 days; June is the wettest month (89 mm) and January the driest (17 mm).

Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).

Planted in autumn

From a month before the first autumn frost, so the roots grow before winter, to the late-planting limit on each crop’s page (about two weeks before the ground freezes, by ten years of weather).