Spencer, IA 51340 Frost Dates
Spencer, IA: when does the frost end?
Around 05/01 is the usual last spring frost, about 246 days away. Fall's first freeze usually shows up around 10/03, roughly 154 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Spencer 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 5 weeks until Spencer'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
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Spencer against the rest of the dataset
At roughly 154 frost-free days, Spencer places 34,245 of 40,283 ZIP codes in this dataset. Within IA, it ranks 891 of 1,042.
Learn more
Before leaning on 51340's figures: the frost range explains how to read the range around Spencer's dates instead of trusting one, while local microclimates explains what one yard in Spencer can differ from the 51340 normal.