Original data
How many times a year the ground freezes and thaws, by city
Every time the temperature crosses freezing, water in the soil and in concrete expands and then relaxes. Do it enough times and it heaves foundations and opens the cracks basements leak through. We counted the freeze-thaw days for 200 US cities from ten years of ERA5 weather reanalysis. The spread is enormous: from 5 a year in Houston to 137 in Lakewood, CO.
The median US city we track crosses freezing 74 times a year.
The northern clay and Mountain-West cities take the most punishment. That matters because frost stress is cumulative: a wall that survives one winter fine can open a seepage path after ten, and the fix is far cheaper before the crack than after.
Own a home in a hard-freeze city? This is the case for keeping water away from the foundation before winter: saturated soil is what freezes and pushes. Gutters, grading, and drainage do not stop the cold, but they cut the water that turns a freeze into pressure against the wall.
Covering weather or housing? This pairs with our water-table data: groundwater supplies the water, freeze-thaw supplies the force. Two independent public sources pointing at the same basement wall.
Methodology
Source is ERA5 reanalysis via the Open-Meteo archive API, daily minimum and maximum temperature for 200cities over 2014–2023. A freeze-thaw day is any day whose low is below 0 °C and whose high is above it, so the ground surface crosses freezing. We report the mean count per year across the ten years.
This is a temperature-crossing count, a proxy for frost stress, not a laboratory freeze-thaw test of a particular foundation. Whether that stress becomes damage depends on how wet the soil is, how well the lot drains, and how the wall was built — all local. Read it as exposure, not a verdict on any one house.
It is also a surface-air measure. Deep soil and a heated basement wall cycle less than the air does, so treat the count as a relative ranking between cities rather than the exact number of times a given wall freezes.
Free to cite or reproduce with a link to this page. Download the full dataset (CSV) ↓
Freeze-thaw cycles per year, every city we track
200 cities, ranked by how many days a year the temperature crosses freezing. A longer bar means more frost stress on the foundation over a winter.
Using this data
The method is above and the source is public, so the analysis is reproducible. Cite this page. Our water-table, expansive clay, flood claims, and permit fee datasets are alongside it.