Planting zone for 94571 — Rio Vista, CA
ZIP code 94571 (Rio Vista, Solano County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F.
Where ZIP 94571 is
Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoomNot the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.
Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9b means →
Frost forecast — next 7 nights
live from the National Weather ServiceLoading the forecast for Rio Vista, CA…
Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.
Frost dates
A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station Antioch Pumping Plt #3, CA — 12 miles away, elevation 59 ft) the median growing season is 343 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.
Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.
When spring arrived in 2026
In 2026, spring leaf-out near 94571 came on Jan 31 — about the same time as the 1991–2020 average (Jan 31).
Jan 312026
Jan 31
The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).
Soil in Rio Vista, CA
The soil mapped at the center of ZIP 94571 is Diablo — clay, well drained.
Map unit: Diablo-Ayar clays, 9 to 30 percent slopes, eroded.
Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 94571; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.
Climate in Rio Vista, CA
Average high and low, by month
Precipitation by month inches
NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Antioch Pumping Plt #3, CA (12 mi away); precipitation: Antioch Pumping Plt #3, CA (12 mi away). Daylight is calculated from latitude.
Nearby ZIP codes
All 8 nearest ZIP codes share zone 9b.
Questions about 94571
What planting zone is ZIP code 94571?
ZIP code 94571 (Rio Vista, CA) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).
How much rain and snow does 94571 get?
About 12.6 inches of precipitation a year (NOAA 1991–2020 normals, Antioch Pumping Plt #3 station).
How hot do summers get in Rio Vista, CA?
The average high peaks at 91 °F in July, with about 64 days a year at 90 °F or more.
What kind of soil does 94571 have?
The USDA soil survey maps Diablo at the center of ZIP 94571: clay, well drained, pH about 7.3 (neutral).
Did spring come early in Rio Vista, CA in 2026?
Spring leaf-out near 94571 came on Jan 31 in 2026, about the same as the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.
What kind of onions grow in Rio Vista, CA?
Intermediate onions: the longest day near 94571 is 14 h 49 min, so day-neutral types bulb best; long-day varieties may not bulb fully.