Eureka, MT 59928 Frost Dates
59928, near Eureka, MT: the frost window
The NOAA station nearest to 59928 does not report a usable frost-date normal for either event, so no last-frost or first-frost figure is shown here. The USDA hardiness zone below is still real: Zone 5a (-20 to -15°F average annual minimum).
Eureka against the rest of the dataset
Eureka's growing season runs about 40 days, ranking 40,250 of 40,283 US ZIP codes measured here, longest to shortest. Within MT, it ranks 387 of 392.
Learn more
Two guides worth reading on 59928: the methodology, on exactly which NOAA and USDA figures feed 59928's numbers, and zone vs. frost date, on why Zone 5a and Eureka's frost date answer different questions.