Natural hazards · Alto

Alto, SD natural hazards

Most of the natural-hazard damage FEMA expects in Alto comes from cold waves, and overall the risk is moderate for a U.S. community.

FEMA National Risk Index, December 2025 · OpenFEMA claims, aid & declarations

Expected damage

How exposed is Alto?

Moderate

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in Alto to be higher than in 51% of U.S. communities, mostly from cold waves and inland flooding.

Cold waves37%Inland flooding28%Tornadoes11%Strong wind6%Wildfire5%Everything else13%

By hazard

What Alto faces

Each hazard’s share of the damage FEMA expects here, and how that compares with the rest of the country.

Cold waves

37% of expected damage

Above average · higher than 65% of U.S. places

Recorded about 14 times a year in the area

Inland flooding

28% of expected damage

Above average · higher than 54% of U.S. places

Recorded about once a year in the area

Tornadoes

11% of expected damage

Well above average · higher than 88% of U.S. places

Recorded about once every 4 years in the area

Strong wind

6% of expected damage

Well above average · higher than 91% of U.S. places

Recorded about 3 times a year in the area

Wildfire

5% of expected damage

Well above average · higher than 96% of U.S. places

Lower here

HailIce stormsWinter weatherHeat wavesEarthquakesLandslidesLightning

Not a risk here

Coastal floodingHurricanesDroughtAvalanchesTsunamisVolcanic activity

Flood risk changes street by street. Check a specific address on FEMA’s flood map, and ask about flood insurance before you buy.

Flood insurance claims

Does Alto flood?

FEMA's records show no paid flood insurance claims in Alto.

of homes in flood zones
are insured

of all homes
are insured

No community discount. Alto isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.

Insurance rates: Roberts County.

Disasters that hit Alto

Federal disasters declared here

None of the disasters declared for Roberts County shows FEMA aid or repair money reaching Alto itself in FEMA’s records.

Brought FEMA money into AltoDeclared for Roberts County only

Roberts County has had 22 natural disasters declared since 1953, most often floods and severe storms.

Around Alto

Alto and the towns around it

Very lowLowModerateHighVery high

Altomostly cold wavesModerate

One Roadmostly cold wavesModerate

Spring Grovemostly cold wavesModerate

Ortleymostly cold wavesModerate

Kosciuskomostly inland floodingModerate

Waubaymostly inland floodingModerate

About these numbers

How to read this page

An average, not a forecastFEMA’s National Risk Index estimates the damage 18 kinds of natural hazards cause in a typical year, from decades of records and models. A quiet decade can follow a bad year.

Compared by rate“Higher than N%” compares yearly damage as a share of what’s here, so a big city isn’t rated riskier just for having more buildings. Alto is smaller than a census tract, so it shares the figures of the tract around its center.

Money that reached townFlood claims are matched to Alto’s own flood-insurance community; household aid to the registrant’s city; repair grants to the Township of Alto. FEMA’s model follows property values, so a place that recently lost many homes can rate lower than it feels.

Sources: FEMA National Risk Index (December 2025); OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Census tracts: U.S. Census Bureau.