Williamsburg, IA 52204 Frost Dates
Williamsburg, IA: when does the frost end?
Typically, the last spring freeze lands around 04/28, roughly 243 days out. Fall's first freeze usually shows up around 10/09, roughly 164 days after the last spring frost.
Zone 5b (-15 to -10°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 Williamsburg, not a forecast for this year.
Stretching the season past the first frost
With roughly 6 weeks until Williamsburg'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
04/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/14 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Williamsburg against the rest of the dataset
Williamsburg's growing season runs about 164 days, ranking 30,936 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 586 of 1,042.
Learn more
Before leaning on 52204's figures: local microclimates explains what one yard in Williamsburg can differ from the 52204 normal, while zone vs. frost date explains why Zone 5b and Williamsburg's frost date answer different questions.