Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 42215 — Cerulean, KY

ZIP code 42215 (Cerulean, Trigg County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 4 and the first fall frost November 2.

Where ZIP 42215 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 4

First frostNov 2

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cerulean, KY…

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 Cerulean, KY

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 4median — 50% chance of a later frost

Safe for tender plantsApril 19only 10% chance of frost after

First fall frostNovember 2median — 10% chance by Oct 20

Growing season211 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 22 and returns around November 13.

From the NOAA station Hopkinsville, KY — 13 miles away, elevation 522 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 42215

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 21 – Mar 7

SpinachSow outdoors · Feb 21 – Mar 14

Broccoli, cabbageStart indoors · Jan 24 – Feb 7

Broccoli, cabbageTransplant · Mar 14 – Mar 28

Onion setsPlant outdoors · Mar 7 – Mar 21

PotatoesPlant outdoors · Mar 14 – Mar 28

LettuceSow outdoors · Mar 7 – Mar 21

Carrots, beetsSow outdoors · Mar 14 – Mar 28

TomatoesStart indoors · Feb 7 – Feb 21

TomatoesTransplant · Apr 11 – Apr 25

Peppers, eggplantStart indoors · Jan 24 – Feb 7

Peppers, eggplantTransplant · Apr 18 – May 2

BeansSow outdoors · Apr 11 – Apr 25

Sweet cornSow outdoors · Apr 11 – Apr 25

Cucumbers, squashSow outdoors · Apr 11 – Apr 25

Fall lettuce, spinachSow outdoors · Sep 7 – Sep 21

GarlicPlant cloves · Oct 19 – Nov 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 4) and first fall frost (Nov 2) 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 42215 came on Mar 1 — about the same time as the 1991–2020 average (Mar 3).

average
Mar 32026
Mar 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).

Native plants for zone 7a in Kentucky

547 plants native to the lower 48 states, recorded in Kentucky, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Cerulean, KY.

Soil in Cerulean, KY

The soil mapped at the center of ZIP 42215 is Nicholson — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables

pH5.5moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter3%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Nicholson silt loam, 6 to 12 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 42215; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cerulean, KY

Summer high88 °Faverage high, July

Winter low27 °Faverage low, January

Hot days42days a year at 90 °F or more

Freezing nights87nights a year at 32 °F or less

Growing degree days4,577base 50 °F — the season’s usable heat

Longest day14 h 42 mindaylight on June 21

Shortest day9 h 37 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation51.6 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hopkinsville, KY (13 mi away); precipitation: Dawson Springs, KY (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

Saint Charles, KY · 12 mi

424087a

Dawson Springs, KY · 13 mi

422417a

Hopkinsville, KY · 14 mi

424457a

Princeton, KY · 14 mi

422407a

Hopkinsville, KY · 14 mi

422117a

Cadiz, KY · 15 mi

Kentucky planting zones →

Questions about 42215

What planting zone is ZIP code 42215?

ZIP code 42215 (Cerulean, KY) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Cerulean, KY?

The median last spring frost (32 °F) near 42215 is April 4; after April 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hopkinsville station.

When is the first frost in Cerulean, KY?

The median first fall frost near 42215 is November 2, giving a median frost-free growing season of 211 days.

When should I plant tomatoes in 42215?

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

How much rain and snow does 42215 get?

About 51.6 inches of precipitation a year (NOAA 1991–2020 normals, Dawson Springs station).

How hot do summers get in Cerulean, KY?

The average high peaks at 88 °F in July, with about 42 days a year at 90 °F or more.

What kind of soil does 42215 have?

The USDA soil survey maps Nicholson at the center of ZIP 42215: silt loam, moderately well drained, pH about 5.5 (moderately acidic).

Did spring come early in Cerulean, KY in 2026?

Spring leaf-out near 42215 came on Mar 1 in 2026, about the same as the 1991–2020 average (Mar 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cerulean, KY?

Intermediate onions: the longest day near 42215 is 14 h 42 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 42215 change?

Yes. The 2012 USDA map put 42215 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.