St. Thomas, ND 58276 Frost Dates
Frost dates for St. Thomas, ND, ZIP 58276
Around 05/04 is the usual last spring frost, about 249 days away. The first fall frost typically arrives around 10/07, about 156 frost-free days later.
St. Thomas sits in USDA Zone 4a (-30 to -25°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 4a around St. Thomas has about 6 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around St. Thomas's last frost
05/04 is the middle of 30 years of NOAA records, not a promise. Plant by 04/19 and you're betting against frost in roughly 9 years out of 10. 05/18 is the safer bet, historically only a 1-in-10 chance of frost that late.
How St. Thomas compares
At roughly 156 frost-free days, St. Thomas places 33,826 of 40,283 ZIP codes in this dataset. Within ND, it ranks 14 of 405.
Learn more
zone vs. frost date explains why Zone 4a and St. Thomas's frost date answer different questions, and the frost range explains how to read the range around St. Thomas's dates instead of trusting one.