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Armstrong County, Pennsylvania

A shallow water table limits basements on 33% of Armstrong County's mapped land, a higher share than 51% of US counties. Shrink-swell clay limits houses without basements on 1%.

None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 51 flood losses here since 2016, 52% of them in buildings with basements. 73% of homes were built before 1980, against 50% nationally; the median home dates from 1959.

Data as of October 13, 2026 · sources

1%

expansive clay: shrink-swell limits slab homes

33%

high water table: limits basements

0%

in drought, October 13, 2026

73%

of homes built before 1980

Soil under Armstrong County

Expansive clay (limits slab homes)0.6%
High water table (limits basements)32.6%
Septic fields very limited94.6%
Clay swell (LEP, by area)1.7%
High-swell land (LEP 6%+)0.6%
Mapped soil420,113 acres
Soil seriesShare hereSeries nationally: high water table
Gilpin30%under 1%
Weikert15%under 1%
Ernest13%n/a
Wharton8%n/a
Bethesda7%n/a
Hazleton7%0%
Indiana County: 37%Butler County: 53%Clarion County: 50%Jefferson County: 42%Westmoreland County: 48%Allegheny County: 31%Venango County: 73%Cambria County: 60%Armstrong County IndianaButlerClarionJeffersonWestmorelandAlleghenyVenangoCambriaArmstrong
Armstrong County (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas PA005 (2025-09-05)

What the numbers mean here

On 33% of Armstrong County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.

Rain over the 12 months to August 2026: 45.91 in, 1.03 in above the 1991-2020 average year of 44.88 in.

USDA rates 95% of the land very limited for septic absorption fields.

Drought

0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 1 of the last 52 weeks; the most was 6% of its area, on the October 21, 2025 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse0%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

51 flood losses since 2016, $1.2 million paid. The worst year was 2018, with 24. Foundations of the buildings, where recorded: 52% basements, 3% slabs, 14% crawl spaces, 31% elevated. Median water depth outside the building: 15.5 in.

YearFlood losses
20160
20179
201824
201910
20201
20210
20220
20230
20243
20252
2026 to date2

Rain

Average year, 1991-202044.88 in
12 months to August 202645.91 in (+1.03)
202542.92 in (-1.96)
Wettest year since 18952018: 65.54 in
Driest year since 18951930: 28.64 in
Days with 1 inch or more, normal at FORD CITY 4 S DAM (7 mi away)9.4

Homes

Housing units32,128
Median year built1959
Built before 198073%
Built 2000 or later10%
Owner-occupied79%
Median value, owner-occupied$157,300
Single-family detached77%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Basement waterproofing, US $3,000 to $10,000 Fixr, February 6, 2026
Sump pump installation, US $800 to $2,000 Fixr, January 31, 2025
Crawl space encapsulation, US $2,000 to $8,000 Fixr, August 29, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Indiana County, PA 23 mi 1% 37%
Butler County, PA 25 mi 1% 53%
Clarion County, PA 27 mi under 1% 50%
Jefferson County, PA 33 mi under 1% 42%
Westmoreland County, PA 35 mi 5% 48%
Allegheny County, PA 36 mi 10% 31%
Venango County, PA 44 mi under 1% 73%
Cambria County, PA 45 mi 0% 60%

Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status