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

Planting zone for 62536 — Glenarm, IL

ZIP code 62536 (Glenarm, Sangamon County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 7 and the first fall frost October 29.

Where ZIP 62536 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 7
First frostOct 29
2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Glenarm, 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 Glenarm, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 7median — 50% chance of a later frost
Safe for tender plantsApril 21only 10% chance of frost after
First fall frostOctober 29median — 10% chance by Oct 16
Growing season205 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 28 and returns around November 7.

From the NOAA station Virden, IL — 11 miles away, elevation 676 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 62536

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 24 – Mar 10
SpinachSow outdoors · Feb 24 – Mar 17
Broccoli, cabbageStart indoors · Jan 27 – Feb 10
Broccoli, cabbageTransplant · Mar 17 – Mar 31
Onion setsPlant outdoors · Mar 10 – Mar 24
PotatoesPlant outdoors · Mar 17 – Mar 31
LettuceSow outdoors · Mar 10 – Mar 24
Carrots, beetsSow outdoors · Mar 17 – Mar 31
TomatoesStart indoors · Feb 10 – Feb 24
TomatoesTransplant · Apr 14 – Apr 28
Peppers, eggplantStart indoors · Jan 27 – Feb 10
Peppers, eggplantTransplant · Apr 21 – May 5
BeansSow outdoors · Apr 14 – Apr 28
Sweet cornSow outdoors · Apr 14 – Apr 28
Cucumbers, squashSow outdoors · Apr 14 – Apr 28
Fall lettuce, spinachSow outdoors · Sep 3 – Sep 17
GarlicPlant cloves · Oct 15 – Nov 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 7) and first fall frost (Oct 29) 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 62536 came on Mar 10 — 15 days earlier than the 1991–2020 average (Mar 25).

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 Glenarm, IL.

Soil in Glenarm, IL

The soil mapped at the center of ZIP 62536 is Assumption — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Assumption silt loam, 5 to 10 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 62536; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Glenarm, IL

Summer high87 °Faverage high, July
Winter low21 °Faverage low, January
Hot days25days a year at 90 °F or more
Freezing nights101nights a year at 32 °F or less
Growing degree days4,040base 50 °F — the season’s usable heat
Longest day14 h 58 mindaylight on June 21
Shortest day9 h 22 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation41.2 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 36 °F, low 21 °F 36°21° JanFebruary: average high 42 °F, low 25 °F 42°25° FebMarch: average high 54 °F, low 34 °F 54°34° MarApril: average high 67 °F, low 45 °F 67°45° AprMay: average high 76 °F, low 55 °F 76°55° MayJune: average high 83 °F, low 65 °F 83°65° JunJuly: average high 87 °F, low 68 °F 87°68° JulAugust: average high 85 °F, low 66 °F 85°66° AugSeptember: average high 80 °F, low 58 °F 80°58° SepOctober: average high 67 °F, low 47 °F 67°47° OctNovember: average high 52 °F, low 35 °F 52°35° NovDecember: average high 41 °F, low 26 °F 41°26° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.24 in precipitation 2.2 JanFebruary: 2.00 in precipitation 2.0 FebMarch: 2.98 in precipitation 3.0 MarApril: 4.37 in precipitation 4.4 AprMay: 4.96 in precipitation 5.0 MayJune: 4.99 in precipitation 5.0 JunJuly: 4.09 in precipitation 4.1 JulAugust: 3.44 in precipitation 3.4 AugSeptember: 3.41 in precipitation 3.4 SepOctober: 3.34 in precipitation 3.3 OctNovember: 3.13 in precipitation 3.1 NovDecember: 2.21 in precipitation 2.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Virden, IL (11 mi away); precipitation: Chatham 1.4 Ese, IL (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

625306a
Divernon, IL · 5 mi
626296a
Chatham, IL · 5 mi
625586a
Pawnee, IL · 6 mi
626156a
Auburn, IL · 6 mi
627196a
Springfield, IL · 9 mi
627226a
Springfield, IL · 9 mi
627236a
Springfield, IL · 9 mi
627266a
Springfield, IL · 9 mi

Illinois planting zones →

Questions about 62536

What planting zone is ZIP code 62536?

ZIP code 62536 (Glenarm, 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 Glenarm, IL?

The median last spring frost (32 °F) near 62536 is April 7; after April 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Virden station.

When is the first frost in Glenarm, IL?

The median first fall frost near 62536 is October 29, giving a median frost-free growing season of 205 days.

When should I plant tomatoes in 62536?

Start tomato seeds indoors around Feb 10 – Feb 24 and set transplants outside around Apr 14 – Apr 28, one to three weeks after the median last frost.

How much rain and snow does 62536 get?

About 41.2 inches of precipitation a year (NOAA 1991–2020 normals, Chatham 1.4 Ese station).

How hot do summers get in Glenarm, IL?

The average high peaks at 87 °F in July, with about 25 days a year at 90 °F or more.

What kind of soil does 62536 have?

The USDA soil survey maps Assumption at the center of ZIP 62536: silt loam, moderately well drained, pH about 6.5 (neutral).

Did spring come early in Glenarm, IL in 2026?

Spring leaf-out near 62536 came on Mar 10 in 2026, 15 days earlier than the 1991–2020 average (Mar 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Glenarm, IL?

Intermediate onions: the longest day near 62536 is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.