Whitehall, MT 59721 Frost Dates
Whitehall, MT: when does the frost end?
The last spring frost here typically falls around 05/09, about 254 days from today. Fall's first freeze usually shows up around 09/27, roughly 139 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Whitehall in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 4 weeks until Whitehall's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/24 and only about 1 year in 10 sees frost after that.
Whitehall against the rest of the dataset
At roughly 139 frost-free days, Whitehall places 37,247 of 40,283 ZIP codes in this dataset. Within MT, it ranks 70 of 392.
Learn more
Before leaning on 59721's figures: the frost range explains how to read the range around Whitehall's dates instead of trusting one, while local microclimates explains what one yard in Whitehall can differ from the 59721 normal.