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

Planting zone for 40070 — Sulphur, KY

ZIP code 40070 (Sulphur, Henry County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 12 and the first fall frost October 25.

Where ZIP 40070 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 12
First frostOct 25
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sulphur, 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 Sulphur, KY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 12median — 50% chance of a later frost
Safe for tender plantsMay 1only 10% chance of frost after
First fall frostOctober 25median — 10% chance by Oct 11
Growing season193 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 3.

From the NOAA station Crestwood 4ne, KY — 12 miles away, elevation 781 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 40070

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 1 – Mar 15
SpinachSow outdoors · Mar 1 – Mar 22
Broccoli, cabbageStart indoors · Feb 1 – Feb 15
Broccoli, cabbageTransplant · Mar 22 – Apr 5
Onion setsPlant outdoors · Mar 15 – Mar 29
PotatoesPlant outdoors · Mar 22 – Apr 5
LettuceSow outdoors · Mar 15 – Mar 29
Carrots, beetsSow outdoors · Mar 22 – Apr 5
TomatoesStart indoors · Feb 15 – Mar 1
TomatoesTransplant · Apr 19 – May 3
Peppers, eggplantStart indoors · Feb 1 – Feb 15
Peppers, eggplantTransplant · Apr 26 – May 10
BeansSow outdoors · Apr 19 – May 3
Sweet cornSow outdoors · Apr 19 – May 3
Cucumbers, squashSow outdoors · Apr 19 – May 3
Fall lettuce, spinachSow outdoors · Aug 30 – Sep 13
GarlicPlant cloves · Oct 11 – Nov 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 12) and first fall frost (Oct 25) 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 40070 came on Mar 8 — 8 days earlier than the 1991–2020 average (Mar 16).

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 Sulphur, KY

The soil mapped at the center of ZIP 40070 is Faywood — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Faywood silty clay loam, 12 to 20 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 40070; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sulphur, KY

Summer high88 °Faverage high, July
Winter low23 °Faverage low, January
Hot days37days a year at 90 °F or more
Freezing nights105nights a year at 32 °F or less
Growing degree days3,944base 50 °F — the season’s usable heat
Longest day14 h 51 mindaylight on June 21
Shortest day9 h 29 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation49.9 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 41 °F, low 23 °F 41°23° JanFebruary: average high 45 °F, low 27 °F 45°27° FebMarch: average high 56 °F, low 33 °F 56°33° MarApril: average high 68 °F, low 44 °F 68°44° AprMay: average high 77 °F, low 54 °F 77°54° MayJune: average high 85 °F, low 62 °F 85°62° JunJuly: average high 88 °F, low 65 °F 88°65° JulAugust: average high 87 °F, low 64 °F 87°64° AugSeptember: average high 81 °F, low 56 °F 81°56° SepOctober: average high 68 °F, low 45 °F 68°45° OctNovember: average high 54 °F, low 34 °F 54°34° NovDecember: average high 44 °F, low 27 °F 44°27° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.52 in precipitation 3.5 JanFebruary: 3.42 in precipitation 3.4 FebMarch: 4.55 in precipitation 4.5 MarApril: 5.11 in precipitation 5.1 AprMay: 6.00 in precipitation 6.0 MayJune: 4.38 in precipitation 4.4 JunJuly: 4.72 in precipitation 4.7 JulAugust: 3.03 in precipitation 3.0 AugSeptember: 3.64 in precipitation 3.6 SepOctober: 3.91 in precipitation 3.9 OctNovember: 3.54 in precipitation 3.5 NovDecember: 4.10 in precipitation 4.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Crestwood 4ne, KY (12 mi away); precipitation: Eminence 4.0 Nw, KY (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

400506b
New Castle, KY · 3 mi
400586b
Port Royal, KY · 4 mi
400556b
Pendleton, KY · 5 mi
400116b
Campbellsburg, KY · 5 mi
400686b
Smithfield, KY · 6 mi
400196b
Eminence, KY · 8 mi
400756b
Turners Station, KY · 9 mi
400316b
La Grange, KY · 9 mi

Kentucky planting zones →

Questions about 40070

What planting zone is ZIP code 40070?

ZIP code 40070 (Sulphur, KY) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Sulphur, KY?

The median last spring frost (32 °F) near 40070 is April 12; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Crestwood 4ne station.

When is the first frost in Sulphur, KY?

The median first fall frost near 40070 is October 25, giving a median frost-free growing season of 193 days.

When should I plant tomatoes in 40070?

Start tomato seeds indoors around Feb 15 – Mar 1 and set transplants outside around Apr 19 – May 3, one to three weeks after the median last frost.

How much rain and snow does 40070 get?

About 49.9 inches of precipitation a year (NOAA 1991–2020 normals, Eminence 4.0 Nw station).

How hot do summers get in Sulphur, KY?

The average high peaks at 88 °F in July, with about 37 days a year at 90 °F or more.

What kind of soil does 40070 have?

The USDA soil survey maps Faywood at the center of ZIP 40070: silty clay loam, well drained, pH about 6.5 (neutral).

Did spring come early in Sulphur, KY in 2026?

Spring leaf-out near 40070 came on Mar 8 in 2026, 8 days earlier than the 1991–2020 average (Mar 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sulphur, KY?

Intermediate onions: the longest day near 40070 is 14 h 51 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 40070 change?

Yes. The 2012 USDA map put 40070 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.