Rock Rapids, IA 51246 Frost Dates
Rock Rapids, 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 10/04, roughly 156 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Rock Rapids 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 Rock Rapids's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Rock Rapids's last frost
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 05/13 and only about 1 year in 10 sees frost after that.
Rock Rapids against the rest of the dataset
At roughly 156 frost-free days, Rock Rapids places 33,630 of 40,283 ZIP codes in this dataset. Within IA, it ranks 862 of 1,042.
Learn more
Before leaning on 51246's figures: local microclimates explains what one yard in Rock Rapids can differ from the 51246 normal, while zone vs. frost date explains why Zone 5a and Rock Rapids's frost date answer different questions.