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

Planting zone for 62655 — Kilbourne, IL

ZIP code 62655 (Kilbourne, Mason County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 17 and the first fall frost October 19.

Where ZIP 62655 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostApr 17
First frostOct 19
2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kilbourne, IL…

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 Kilbourne, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 17median — 50% chance of a later frost
Safe for tender plantsMay 3only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 1
Growing season185 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 5 and returns around October 29.

From the NOAA station Havana, IL — 10 miles away, elevation 463 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 62655

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 6 – Mar 20
SpinachSow outdoors · Mar 6 – Mar 27
Broccoli, cabbageStart indoors · Feb 6 – Feb 20
Broccoli, cabbageTransplant · Mar 27 – Apr 10
Onion setsPlant outdoors · Mar 20 – Apr 3
PotatoesPlant outdoors · Mar 27 – Apr 10
LettuceSow outdoors · Mar 20 – Apr 3
Carrots, beetsSow outdoors · Mar 27 – Apr 10
TomatoesStart indoors · Feb 20 – Mar 6
TomatoesTransplant · Apr 24 – May 8
Peppers, eggplantStart indoors · Feb 6 – Feb 20
Peppers, eggplantTransplant · May 1 – May 15
BeansSow outdoors · Apr 24 – May 8
Sweet cornSow outdoors · Apr 24 – May 8
Cucumbers, squashSow outdoors · Apr 24 – May 8
Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7
GarlicPlant cloves · Oct 5 – Nov 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 19) 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 62655 came on Mar 11 — 16 days earlier than the 1991–2020 average (Mar 27).

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 6a in Illinois

610 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 78

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 108

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 220

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 178

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 9

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °F

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 Kilbourne, IL.

Soil in Kilbourne, IL

The soil mapped at the center of ZIP 62655 is Bloomfield — fine sand, somewhat excessively drained.

TextureFine sanddrains and warms fast; dries out and needs more feeding
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter2%moderate
Hydrologic groupAwater soaks in fast
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Bloomfield fine sand, 1 to 7 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 62655; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kilbourne, IL

Summer high88 °Faverage high, July
Winter low16 °Faverage low, January
Hot days35days a year at 90 °F or more
Freezing nights133nights a year at 32 °F or less
Growing degree days3,666base 50 °F — the season’s usable heat
Longest day15 h 02 mindaylight on June 21
Shortest day9 h 18 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation41 inper year, rain and melted snow
Snowfall28 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 34 °F, low 16 °F 34°16° JanFebruary: average high 39 °F, low 20 °F 39°20° FebMarch: average high 51 °F, low 30 °F 51°30° MarApril: average high 64 °F, low 41 °F 64°41° AprMay: average high 75 °F, low 53 °F 75°53° MayJune: average high 85 °F, low 62 °F 85°62° JunJuly: average high 88 °F, low 65 °F 88°65° JulAugust: average high 86 °F, low 63 °F 86°63° AugSeptember: average high 80 °F, low 54 °F 80°54° SepOctober: average high 68 °F, low 42 °F 68°42° OctNovember: average high 52 °F, low 32 °F 52°32° NovDecember: average high 39 °F, low 22 °F 39°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 2.20 in precipitation, 9.7 in snowfall 2.2❄10 JanFebruary: 2.18 in precipitation, 5.8 in snowfall 2.2❄6 FebMarch: 2.72 in precipitation, 3.2 in snowfall 2.7❄3 MarApril: 4.22 in precipitation, 1.2 in snowfall 4.2❄1 AprMay: 5.08 in precipitation 5.1 MayJune: 4.73 in precipitation 4.7 JunJuly: 4.18 in precipitation 4.2 JulAugust: 4.02 in precipitation 4.0 AugSeptember: 3.26 in precipitation 3.3 SepOctober: 3.37 in precipitation 3.4 OctNovember: 2.73 in precipitation, 1.1 in snowfall 2.7❄1 NovDecember: 2.35 in precipitation, 6.9 in snowfall 2.4❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Havana, IL (10 mi away); precipitation: Havana, IL (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

626736a
Oakford, IL · 5 mi
626336a
Easton, IL · 7 mi
626446a
Havana, IL · 9 mi
626176a
Bath, IL · 10 mi
626276a
Chandlerville, IL · 10 mi
626756a
Petersburg, IL · 12 mi
626646a
Mason City, IL · 14 mi
626596a
Lincoln'S New Salem, IL · 14 mi

Illinois planting zones →

Questions about 62655

What planting zone is ZIP code 62655?

ZIP code 62655 (Kilbourne, IL) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Kilbourne, IL?

The median last spring frost (32 °F) near 62655 is April 17; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Havana station.

When is the first frost in Kilbourne, IL?

The median first fall frost near 62655 is October 19, giving a median frost-free growing season of 185 days.

When should I plant tomatoes in 62655?

Start tomato seeds indoors around Feb 20 – Mar 6 and set transplants outside around Apr 24 – May 8, one to three weeks after the median last frost.

How much rain and snow does 62655 get?

About 41 inches of precipitation a year and 28 inches of snowfall (NOAA 1991–2020 normals, Havana station).

How hot do summers get in Kilbourne, IL?

The average high peaks at 88 °F in July, with about 35 days a year at 90 °F or more.

What kind of soil does 62655 have?

The USDA soil survey maps Bloomfield at the center of ZIP 62655: fine sand, somewhat excessively drained, pH about 6.2 (slightly acidic).

Did spring come early in Kilbourne, IL in 2026?

Spring leaf-out near 62655 came on Mar 11 in 2026, 16 days earlier than the 1991–2020 average (Mar 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Kilbourne, IL?

Long-day onions: the longest day near 62655 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 62655 change?

Yes. The 2012 USDA map put 62655 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.