Morristown, SD 57645 Frost Dates
When can you plant in Morristown, SD?
The last spring frost here typically falls around 05/09, about 254 days from today. The first fall frost typically arrives around 09/30, about 143 frost-free days later.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Morristown, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in Morristown before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/09 isn't a guarantee
05/09 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/24 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Morristown compares
At roughly 143 frost-free days, Morristown places 36,684 of 40,283 ZIP codes in this dataset. Within SD, it ranks 280 of 378.
Learn more
local microclimates covers what one yard in Morristown can differ from the 57645 normal. zone vs. frost date covers why Zone 4b and Morristown's frost date answer different questions.