Address reportCitiesCalifornia › Ontario

Ontario, CA

Earthquake hazard, typical weather and growing season from public federal data. Population 167,500.

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

92.2° in July, 39.6° in December

Heads up: the nearest station with a full 30-year record is MITCHELL CAVERNS, CA US, about 24.9 miles from here. Treat these as regional rather than local — terrain, elevation and water can change a lot in that distance.

Thirty-year averages, not a forecast. Any individual year can differ substantially.

MonthHighLowRainSnow
Jan53.9°40.1°1.27"0.2"
Feb55.4°41.2°1.84"0.1"
Mar61.9°44.7°1.58"0.4"
Apr67.8°49.7°0.61"0"
May77°58.3°0.16"0"
Jun87.3°68.6°0.05"0"
Jul92.2°73.1°1.08"0"
Aug90.8°72.4°0.6"0"
Sep85°67.8°0.7"0"
Oct73.7°56.6°0.57"0"
Nov62.4°46.7°0.5"0"
Dec53.3°39.6°1.63"0.1"

NOAA/NCEI 1991–2020 U.S. Climate Normals — station MITCHELL CAVERNS, CA US, 24.9 mi away.

Growing season zone 10a

272 frost-free days

Heads up: the nearest station with a full 30-year record is MITCHELL CAVERNS, CA US, about 24.9 miles from here. Treat these as regional rather than local — terrain, elevation and water can change a lot in that distance.

Last spring frost around March 6, first fall frost around December 8. Roughly half of years see frost outside that window.

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

What this page does not tell you

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