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

Planting zone for 95248 — Rail Road Flat, CA

ZIP code 95248 (Rail Road Flat, Calaveras County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is May 7 and the first fall frost October 28.

Where ZIP 95248 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostMay 7
First frostOct 28
2012 zone9a

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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Rail Road Flat, 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 Rail Road Flat, CA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 7median — 50% chance of a later frost
Safe for tender plantsMay 31only 10% chance of frost after
First fall frostOctober 28median — 10% chance by Oct 5
Growing season169 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around November 14.

From the NOAA station Calaveras Big Trees, CA — 9 miles away, elevation 4,695 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 95248

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 26 – Apr 9
SpinachSow outdoors · Mar 26 – Apr 16
Broccoli, cabbageStart indoors · Feb 26 – Mar 12
Broccoli, cabbageTransplant · Apr 16 – Apr 30
Onion setsPlant outdoors · Apr 9 – Apr 23
PotatoesPlant outdoors · Apr 16 – Apr 30
LettuceSow outdoors · Apr 9 – Apr 23
Carrots, beetsSow outdoors · Apr 16 – Apr 30
TomatoesStart indoors · Mar 12 – Mar 26
TomatoesTransplant · May 14 – May 28
Peppers, eggplantStart indoors · Feb 26 – Mar 12
Peppers, eggplantTransplant · May 21 – Jun 4
BeansSow outdoors · May 14 – May 28
Sweet cornSow outdoors · May 14 – May 28
Cucumbers, squashSow outdoors · May 14 – May 28
Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16
GarlicPlant cloves · Oct 14 – Nov 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 7) and first fall frost (Oct 28) 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 95248 came on Jan 30 — 9 days earlier than the 1991–2020 average (Feb 8).

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 Rail Road Flat, CA

The soil mapped at the center of ZIP 95248 is Iron Mountain — gravelly sandy loam, somewhat excessively drained.

TextureGravelly sandy loamdrains and warms fast; dries out and needs more feeding
pH5.4strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter5%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Iron Mountain-Crozier-Rock outcrop complex, 15 to 60 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 95248; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rail Road Flat, CA

Summer high81 °Faverage high, July
Winter low30 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights115nights a year at 32 °F or less
Growing degree days2,183base 50 °F — the season’s usable heat
Longest day14 h 50 mindaylight on June 21
Shortest day9 h 30 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation40.6 inper year, rain and melted snow
Snowfall4 inper year; 1 days with snow on the ground

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 45 °F, low 30 °F 45°30° JanFebruary: average high 46 °F, low 30 °F 46°30° FebMarch: average high 49 °F, low 32 °F 49°32° MarApril: average high 54 °F, low 35 °F 54°35° AprMay: average high 63 °F, low 42 °F 63°42° MayJune: average high 73 °F, low 49 °F 73°49° JunJuly: average high 81 °F, low 56 °F 81°56° JulAugust: average high 80 °F, low 55 °F 80°55° AugSeptember: average high 74 °F, low 51 °F 74°51° SepOctober: average high 64 °F, low 43 °F 64°43° OctNovember: average high 52 °F, low 34 °F 52°34° NovDecember: average high 44 °F, low 30 °F 44°30° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″8″January: 7.34 in precipitation, 0.1 in snowfall 7.3 JanFebruary: 6.91 in precipitation, 1.7 in snowfall 6.9❄2 FebMarch: 6.39 in precipitation, 1.5 in snowfall 6.4❄2 MarApril: 3.36 in precipitation 3.4 AprMay: 2.14 in precipitation 2.1 MayJune: 0.49 in precipitation 0.5 JunJuly: 0.00 in precipitation 0.0 JulAugust: 0.04 in precipitation 0.0 AugSeptember: 0.27 in precipitation 0.3 SepOctober: 2.15 in precipitation 2.1 OctNovember: 3.95 in precipitation 4.0 NovDecember: 7.52 in precipitation, 0.4 in snowfall 7.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Calaveras Big Trees, CA (9 mi away); precipitation: W Pt, CA (6 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.

952578b
Wilseyville, CA · 4 mi
952469a
Mountain Ranch, CA · 5 mi
952329a
Glencoe, CA · 7 mi
952559a
West Point, CA · 7 mi
952459a
Mokelumne Hill, CA · 8 mi
952248b
Avery, CA · 10 mi
952338b
Hathaway Pines, CA · 10 mi
956659a
Pine Grove, CA · 12 mi

California planting zones →

Questions about 95248

What planting zone is ZIP code 95248?

ZIP code 95248 (Rail Road Flat, CA) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Rail Road Flat, CA?

The median last spring frost (32 °F) near 95248 is May 7; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Calaveras Big Trees station.

When is the first frost in Rail Road Flat, CA?

The median first fall frost near 95248 is October 28, giving a median frost-free growing season of 169 days.

When should I plant tomatoes in 95248?

Start tomato seeds indoors around Mar 12 – Mar 26 and set transplants outside around May 14 – May 28, one to three weeks after the median last frost.

How much rain and snow does 95248 get?

About 40.6 inches of precipitation a year and 4 inches of snowfall (NOAA 1991–2020 normals, W Pt station).

How hot do summers get in Rail Road Flat, CA?

The average high peaks at 81 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 95248 have?

The USDA soil survey maps Iron Mountain at the center of ZIP 95248: gravelly sandy loam, somewhat excessively drained, pH about 5.4 (strongly acidic).

Did spring come early in Rail Road Flat, CA in 2026?

Spring leaf-out near 95248 came on Jan 30 in 2026, 9 days earlier than the 1991–2020 average (Feb 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rail Road Flat, CA?

Intermediate onions: the longest day near 95248 is 14 h 50 min, so day-neutral types bulb best; long-day varieties may not bulb fully.