Northwood, IA 50459 Frost Dates
50459, near Northwood, IA: the frost window
The last spring frost here typically falls around 05/04, about 249 days from today. Fall's first freeze usually shows up around 10/04, roughly 152 days after the last spring frost.
Zone 5a (-20 to -15°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 Northwood, not a forecast for this year.
Stretching the season past the first frost
Northwood's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
05/04 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/21 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/16 and only about 1 year in 10 sees frost after that.
Northwood against the rest of the dataset
Northwood's growing season runs about 152 days, ranking 34,782 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 948 of 1,042.
Learn more
Two guides worth reading on 50459: the frost range, on how to read the range around Northwood's dates instead of trusting one, and local microclimates, on what one yard in Northwood can differ from the 50459 normal.