Address reportCitiesAlaska › Anchorage

Anchorage, AK

Earthquake hazard, typical weather and growing season from public federal data. Population 300,950.

Flood zone: it depends on the exact parcel

There is no such thing as a flood zone for a whole city. Two houses on the same street can sit in different zones, and it is the single fact here that changes most over a short distance. So this page does not guess one.

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Earthquake hazard very-high

Design category D

Very high seismic hazard — at or near a major active fault. Very strong ground shaking is likely and the most stringent seismic-design provisions apply. A site-specific ground-motion study is typically required. The ASCE 7 Seismic Design Category here is D. (Short-period design value Ss ≈ 1.5 g — the standard headline measure of ground-shaking hazard.)

USGS Seismic Design Web Services (ASCE 7), assuming Site Class D — stiff or unknown soil. Real soil conditions can move the category either way.

Typical weather not published

The nearest weather station with a full 30-year record is MCGRATH AP, AK US, about 103.3 miles away. That is far enough that its normals describe a different place, so they are not shown here rather than presented as if they were Anchorage's.

NOAA/NCEI publishes normals per station, not per city. Sparse station coverage is a real gap in some areas, and this is what that gap looks like.

Growing season zone 3a

The hardiness zone below is ZIP-level and stands on its own, but the frost dates come from KALTAG AP, AK US about 158.7 miles away — too far to state as this city's, so they are omitted.

2023 USDA Plant Hardiness Zone Map and NOAA/NCEI 1991–2020 frost normals.

What this page does not tell you

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