SnowLoadCheck

Mifflin County, PA Roof Snow Load - 20 psf

What ASCE 7 says about snow load in Mifflin County

Moderate
20 psf

That's Mifflin County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. 17.5 psf is what the ground-load formula alone gives; Mifflin County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.

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.

Mifflin County in numbers

Where Mifflin County's figure sits nationally

Out of 2,758 rated US counties, Mifflin County sits at #751, the top 27% nationally - #36 of 38 within Pennsylvania. 20.9 psf is Pennsylvania's typical county figure - Mifflin County comes in 0.9 psf under it.

Near 40.6016°N 77.6518°W, FIPS 42087: Mifflin County counts 45,935 residents and a 25 psf map value, which the code's own factors turn into 20 psf.

How much it actually snows in Mifflin County

Most winters bring Mifflin County roughly 26.2 in. of snow - NOAA's normal at LEWISTOWN, PA US, 4.5 mi off. (fresh vs. packed vs. ice explains why.)

Read this before you rely on it

Mifflin 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 Mifflin County's county-wide figure. Details: the calculation guide.