Arkansas adopts the 2021 International Residential Code as Volume III of the Arkansas Fire Prevention Code but puts no frost line depth on any page of its own, so a reader gets the number from the city or county building official enforcing the code locally.
Arkansas leaves the frost line depth to the local building department, which is where the number for an address comes from.
The State Fire Marshal’s Office encourages Arkansas cities and counties to join with the Arkansas State Fire Marshal's Office in our effort to enforce the AFPC by adopting the Fire Code as a local ordinance.Arkansas Fire Prevention Code Rules, 2021 Edition, Foreword and Definitions, Arkansas Department of Public Safety, Division of Emergency Management, State Fire Marshal's Office, read September 23, 2026. Read it at the source
That makes the building department issuing the permit the office with the number, and it is a short call: the counter gives the depth for the address, and the same call settles whether a deck footing or a slab edge needs a footing inspection before the concrete goes in. What Arkansas does publish is below, and it is worth having in hand first.
The air freezing index is the quantity the frost provisions of the model codes are written on: add up how far each day’s mean temperature fell below freezing over a winter, in degree days, and take the deepest run the winter managed. It measures how much cold the ground had to absorb, which is why it is the honest way to set one place beside another. Fayetteville is the coldest of the 2 cities on the record in Arkansas.
103degree days
average freezing index a winter
Fayetteville Drake Field
| City | State | Freezing index | Once a century | Nights below freezing |
|---|---|---|---|---|
| Fayetteville | Arkansas | 103 | 377 | 95 |
| Little Rock | Arkansas | 42 | 164 | 54 |
Computed from NOAA National Centers for Environmental Information, Global Historical Climatology Network daily temperature records for each station, from 1951 onward. These are measurements of winter, not depths.
Only a handful of states answer with one number for the whole state, and they are the only codes that can be set beside each other directly. Ranked by the freezing index at their own reference cities, with Arkansas marked at 73 degree days for comparison against what those codes settled on:
Left to right, the mildest winters to the hardest. The figure on the right is what that state wrote into its code.
The nearest by winter are North Carolina at 12 inches, Massachusetts at 4 feet and Connecticut at 42 inches. That is a reading of other states’ codes rather than a depth for an address in Arkansas: soil, drainage, snow cover and local amendments all move the figure, and the building department issuing the permit is the office whose number binds.
Arkansas code read September 23, 2026 from Arkansas Fire Prevention Code Rules, 2021 Edition, Foreword and Definitions, Arkansas Department of Public Safety, Division of Emergency Management, State Fire Marshal's Office. Codes are amended and a local amendment can be deeper than the state figure, so the building department issuing the permit has the number that binds. Every state is on the frost line depth hub.