Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 95973 — Chico, CA

ZIP code 95973 (Chico, Butte County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is March 4 and the first fall frost November 17.

Where ZIP 95973 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not 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.

Zone9b25 to 30 °F
Coldest night−3.9 to −1.1 °C
Last frostMar 4
First frostNov 17
2012 zone9a

Was 9a on the 2012 map — half a zone warmer now. 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 Service

Loading the forecast for Chico, 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 in Chico, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 4median — 50% chance of a later frost
Safe for tender plantsApril 2only 10% chance of frost after
First fall frostNovember 17median — 10% chance by Nov 1
Growing season257 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 5 and returns around December 3.

From the NOAA station Chico Univ Farm, CA — 13 miles away, elevation 184 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 95973

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 21 – Feb 4
SpinachSow outdoors · Jan 21 – Feb 11
Broccoli, cabbageStart indoors · Dec 24 – Jan 7
Broccoli, cabbageTransplant · Feb 11 – Feb 25
Onion setsPlant outdoors · Feb 4 – Feb 18
PotatoesPlant outdoors · Feb 11 – Feb 25
LettuceSow outdoors · Feb 4 – Feb 18
Carrots, beetsSow outdoors · Feb 11 – Feb 25
TomatoesStart indoors · Jan 7 – Jan 21
TomatoesTransplant · Mar 11 – Mar 25
Peppers, eggplantStart indoors · Dec 24 – Jan 7
Peppers, eggplantTransplant · Mar 18 – Apr 1
BeansSow outdoors · Mar 11 – Mar 25
Sweet cornSow outdoors · Mar 11 – Mar 25
Cucumbers, squashSow outdoors · Mar 11 – Mar 25
Fall lettuce, spinachSow outdoors · Sep 22 – Oct 6
GarlicPlant cloves · Nov 3 – Dec 8
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 4) and first fall frost (Nov 17) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 95973 came on Jan 29 — 3 days earlier than the 1991–2020 average (Feb 1).

JanFebMarAprMayJun

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 Chico, CA

The soil mapped at the center of ZIP 95973 is Doemill — gravelly loam, somewhat poorly drained.

TextureGravelly loama good balance for most vegetables
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter5.78%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Doemill-Jokerst , 3 to 8 percent slopes.

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 95973; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chico, CA

Summer high95 °Faverage high, July
Winter low36 °Faverage low, January
Hot days99days a year at 90 °F or more
Freezing nights40nights a year at 32 °F or less
Growing degree days4,667base 50 °F — the season’s usable heat
Longest day15 h 00 mindaylight on June 21
Shortest day9 h 20 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation28.4 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 56 °F, low 36 °F 56°36° JanFebruary: average high 62 °F, low 38 °F 62°38° FebMarch: average high 67 °F, low 42 °F 67°42° MarApril: average high 73 °F, low 45 °F 73°45° AprMay: average high 81 °F, low 52 °F 81°52° MayJune: average high 89 °F, low 57 °F 89°57° JunJuly: average high 95 °F, low 61 °F 95°61° JulAugust: average high 94 °F, low 59 °F 94°59° AugSeptember: average high 91 °F, low 55 °F 91°55° SepOctober: average high 80 °F, low 47 °F 80°47° OctNovember: average high 65 °F, low 40 °F 65°40° NovDecember: average high 57 °F, low 36 °F 57°36° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 5.64 in precipitation 5.6 JanFebruary: 4.87 in precipitation 4.9 FebMarch: 3.94 in precipitation 3.9 MarApril: 2.20 in precipitation 2.2 AprMay: 1.39 in precipitation 1.4 MayJune: 0.65 in precipitation 0.7 JunJuly: 0.04 in precipitation 0.0 JulAugust: 0.14 in precipitation 0.1 AugSeptember: 0.27 in precipitation 0.3 SepOctober: 1.77 in precipitation 1.8 OctNovember: 2.61 in precipitation 2.6 NovDecember: 4.83 in precipitation 4.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Chico Univ Farm, CA (13 mi away); precipitation: Chico 2.9 W, CA (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

959279a
Chico, CA · 6 mi
960929b
Vina, CA · 9 mi
959269b
Chico, CA · 9 mi
959769a
Chico, CA · 10 mi
959299a
Chico, CA · 10 mi
959429a
Forest Ranch, CA · 11 mi
959519b
Hamilton City, CA · 13 mi
959289b
Chico, CA · 14 mi

All 6 ZIP codes in Chico → · California planting zones →

Questions about 95973

What planting zone is ZIP code 95973?

ZIP code 95973 (Chico, 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).

When is the last frost in Chico, CA?

The median last spring frost (32 °F) near 95973 is March 4; after April 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Chico Univ Farm station.

When is the first frost in Chico, CA?

The median first fall frost near 95973 is November 17, giving a median frost-free growing season of 257 days.

When should I plant tomatoes in 95973?

Start tomato seeds indoors around Jan 7 – Jan 21 and set transplants outside around Mar 11 – Mar 25, one to three weeks after the median last frost.

How much rain and snow does 95973 get?

About 28.4 inches of precipitation a year (NOAA 1991–2020 normals, Chico 2.9 W station).

How hot do summers get in Chico, CA?

The average high peaks at 95 °F in July, with about 99 days a year at 90 °F or more.

What kind of soil does 95973 have?

The USDA soil survey maps Doemill at the center of ZIP 95973: gravelly loam, somewhat poorly drained, pH about 6.1 (slightly acidic).

Did spring come early in Chico, CA in 2026?

Spring leaf-out near 95973 came on Jan 29 in 2026, 3 days earlier than the 1991–2020 average (Feb 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Chico, CA?

Long-day onions: the longest day near 95973 is 15 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 95973 change?

Yes. The 2012 USDA map put 95973 in zone 9a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.