Lyon County, IA Roof Snow Load - 28 psf
What ASCE 7 says about snow load in Lyon County
That's Lyon County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from.
Converted to something you can actually eyeball on a roof: about 61.6 in. of fresh powder, 22.4 in. once it settles and packs down, or just 5.6 in. if it's turned to ice. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Lyon County at a glance
- Design roof snow load28 psf
- Ground snow load, ASCE 7 map40 psf
- National rank#259 of 2,758
- Iowa rank#3 of 99
- Population12,378
- Annual snowfall, NOAA normal34.9 in.
- FIPS19119
Where Lyon County's figure sits nationally
Out of 2,758 rated US counties, Lyon County sits at #259, the top 9% nationally - #3 of 99 within Iowa. 21.7 psf is Iowa's typical county figure - Lyon County beats it by 6.3 psf.
Near 43.3836°N 96.2072°W, FIPS 19119: Lyon County counts 12,378 residents and a 40 psf map value, which the code's own factors turn into 28 psf.
How much it actually snows in Lyon County
Most winters bring Lyon County roughly 34.9 in. of snow - NOAA's normal at ROCK RAPIDS, IA US, 3.7 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Lyon County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.
Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Lyon County's county-wide figure. (How this figure is calculated.)