Gallatin County, MT Roof Snow Load - Case Study Area
Gallatin County, MT: no map figure, on purpose
ASCE 7's own snow load map has no single figure for Gallatin County: the terrain is complex enough that the code (§7.2) requires an elevation-specific study rather than a county-wide value. That is the map being accurate, not a data gap.
FIPS 30031, population 126,984. 386 US counties get this same case-study treatment; Gallatin County is one of them.
Gallatin County, MT: quick facts
- Population126,984
- Annual snowfall, NOAA normal44.7 in.
- FIPS30031
Gallatin County: average annual snowfall
Gallatin County sees about 44.7 in. of snow most winters, per the ENNIS, MT US station's 1991-2020 NOAA normal. That station is far enough away (29.3 mi) that local snowfall - especially at a different elevation or near a lake - can run noticeably higher or lower than this figure. See the density guide.
Read this before you use Gallatin County's figure
The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.
A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.