Sweet Grass County, MT Roof Snow Load - 20 psf
What ASCE 7 says about snow load in Sweet Grass County
That's Sweet Grass County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 17.5 psf the base ground-load formula gives.
Converted to something you can actually eyeball on a roof: about 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 in. if it's turned to ice. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.
Sweet Grass County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#1,239 of 2,758
- Montana rank#18 of 29
- Population3,757
- Annual snowfall, NOAA normal54.6 in.
- FIPS30097
Where Sweet Grass County's figure sits nationally
Out of 2,758 rated US counties, Sweet Grass County sits at #1,239, the top 45% nationally - #18 of 29 within Montana. Montana counties average 19 psf; Sweet Grass County runs 1 psf higher than that.
Near 45.8113°N 109.9448°W, FIPS 30097: Sweet Grass County counts 3,757 residents and a 25 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in Sweet Grass County
Most winters bring Sweet Grass County roughly 54.6 in. of snow - NOAA's normal at BIG TIMBER, MT US, 1.5 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Sweet Grass 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 Sweet Grass County's county-wide figure. See the methodology guide.