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

Planting zone for 94515 — Calistoga, CA

ZIP code 94515 (Calistoga, Napa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is March 2 and the first fall frost November 23.

Where ZIP 94515 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 2
First frostNov 23
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 Calistoga, 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 Calistoga, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 2median — 50% chance of a later frost
Safe for tender plantsApril 18only 10% chance of frost after
First fall frostNovember 23median — 10% chance by Nov 1
Growing season263 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 23 and returns around December 6.

From the NOAA station Calistoga, CA — 3 miles away, elevation 400 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 94515

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 19 – Feb 2
SpinachSow outdoors · Jan 19 – Feb 9
Broccoli, cabbageStart indoors · Dec 22 – Jan 5
Broccoli, cabbageTransplant · Feb 9 – Feb 23
Onion setsPlant outdoors · Feb 2 – Feb 16
PotatoesPlant outdoors · Feb 9 – Feb 23
LettuceSow outdoors · Feb 2 – Feb 16
Carrots, beetsSow outdoors · Feb 9 – Feb 23
TomatoesStart indoors · Jan 5 – Jan 19
TomatoesTransplant · Mar 9 – Mar 23
Peppers, eggplantStart indoors · Dec 22 – Jan 5
Peppers, eggplantTransplant · Mar 16 – Mar 30
BeansSow outdoors · Mar 9 – Mar 23
Sweet cornSow outdoors · Mar 9 – Mar 23
Cucumbers, squashSow outdoors · Mar 9 – Mar 23
Fall lettuce, spinachSow outdoors · Sep 28 – Oct 12
GarlicPlant cloves · Nov 9 – Dec 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 2) and first fall frost (Nov 23) 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 94515 came on Jan 23 — 8 days earlier than the 1991–2020 average (Jan 31).

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 Calistoga, CA

The soil mapped at the center of ZIP 94515 is Kidd — loam, well drained.

TextureLoama good balance for most vegetables
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Rock outcrop-Kidd complex, 50 to 75 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 94515; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Calistoga, CA

Summer high90 °Faverage high, July
Winter low39 °Faverage low, January
Hot days71days a year at 90 °F or more
Freezing nights36nights a year at 32 °F or less
Growing degree days3,994base 50 °F — the season’s usable heat
Longest day14 h 52 mindaylight on June 21
Shortest day9 h 28 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation38.6 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°32 °FJanuary: average high 59 °F, low 39 °F 59°39° JanFebruary: average high 62 °F, low 41 °F 62°41° FebMarch: average high 66 °F, low 43 °F 66°43° MarApril: average high 70 °F, low 44 °F 70°44° AprMay: average high 77 °F, low 49 °F 77°49° MayJune: average high 85 °F, low 53 °F 85°53° JunJuly: average high 90 °F, low 55 °F 90°55° JulAugust: average high 89 °F, low 54 °F 89°54° AugSeptember: average high 87 °F, low 52 °F 87°52° SepOctober: average high 79 °F, low 47 °F 79°47° OctNovember: average high 66 °F, low 42 °F 66°42° NovDecember: average high 58 °F, low 39 °F 58°39° Dec

Precipitation by month inches

0″2″4″6″8″January: 7.94 in precipitation 7.9 JanFebruary: 7.07 in precipitation 7.1 FebMarch: 5.89 in precipitation 5.9 MarApril: 2.32 in precipitation 2.3 AprMay: 1.37 in precipitation 1.4 MayJune: 0.29 in precipitation 0.3 JunJuly: 0.01 in precipitation 0.0 JulAugust: 0.03 in precipitation 0.0 AugSeptember: 0.12 in precipitation 0.1 SepOctober: 1.83 in precipitation 1.8 OctNovember: 3.76 in precipitation 3.8 NovDecember: 7.95 in precipitation 8.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Calistoga, CA (3 mi away); precipitation: Calistoga, CA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

954049b
Santa Rosa, CA · 9 mi
954619a
Middletown, CA · 9 mi
945769b
Deer Park, CA · 10 mi
945089b
Angwin, CA · 10 mi
945679a
Pope Valley, CA · 11 mi
954099b
Santa Rosa, CA · 12 mi
954039a
Santa Rosa, CA · 12 mi
945749b
Saint Helena, CA · 12 mi

California planting zones →

Questions about 94515

What planting zone is ZIP code 94515?

ZIP code 94515 (Calistoga, 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 Calistoga, CA?

The median last spring frost (32 °F) near 94515 is March 2; after April 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Calistoga station.

When is the first frost in Calistoga, CA?

The median first fall frost near 94515 is November 23, giving a median frost-free growing season of 263 days.

When should I plant tomatoes in 94515?

Start tomato seeds indoors around Jan 5 – Jan 19 and set transplants outside around Mar 9 – Mar 23, one to three weeks after the median last frost.

How much rain and snow does 94515 get?

About 38.6 inches of precipitation a year (NOAA 1991–2020 normals, Calistoga station).

How hot do summers get in Calistoga, CA?

The average high peaks at 90 °F in July, with about 71 days a year at 90 °F or more.

What kind of soil does 94515 have?

The USDA soil survey maps Kidd at the center of ZIP 94515: loam, well drained, pH about 6.1 (slightly acidic).

Did spring come early in Calistoga, CA in 2026?

Spring leaf-out near 94515 came on Jan 23 in 2026, 8 days earlier than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Calistoga, CA?

Intermediate onions: the longest day near 94515 is 14 h 52 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 94515 change?

Yes. The 2012 USDA map put 94515 in zone 9a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.