Riggins, ID 83547 Frost Dates
Riggins, ID: when does the frost end?
Around 05/06 is the usual last spring frost, about 251 days away. Fall's first freeze usually shows up around 10/09, roughly 155 days after the last spring frost.
Riggins sits in USDA Zone 6b (-5 to 0°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
With roughly 6 weeks until Riggins's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/06 isn't a guarantee
05/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Riggins against the rest of the dataset
At roughly 155 frost-free days, Riggins places 34,108 of 40,283 ZIP codes in this dataset. Within ID, it ranks 95 of 320.
Learn more
Before leaning on 83547's figures: local microclimates explains what one yard in Riggins can differ from the 83547 normal, while zone vs. frost date explains why Zone 6b and Riggins's frost date answer different questions.