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

Planting zone for 60955 — Onarga, IL

ZIP code 60955 (Onarga, Iroquois County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 25 and the first fall frost October 20.

Where ZIP 60955 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostApr 25
First frostOct 20
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Onarga, 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 Onarga, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 10only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 2
Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 13 and returns around October 31.

From the NOAA station Piper City, IL — 11 miles away, elevation 669 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 60955

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 25 – Sep 8
GarlicPlant cloves · Oct 6 – Nov 10
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 20) 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 60955 came on Mar 15 — 17 days earlier than the 1991–2020 average (Apr 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).

Soil in Onarga, IL

The soil mapped at the center of ZIP 60955 is Sawmill — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.7neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter3%moderate
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if drained and either protected from flooding or not frequently flooded during the growing seasonUSDA classification

Map unit: Sawmill silty clay loam, heavy till plain, 0 to 2 percent slopes, frequently flooded.

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 60955; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Onarga, IL

Summer high88 °Faverage high, July
Winter low16 °Faverage low, January
Hot days28days a year at 90 °F or more
Freezing nights134nights a year at 32 °F or less
Growing degree days3,486base 50 °F — the season’s usable heat
Longest day15 h 06 mindaylight on June 21
Shortest day9 h 15 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation40.1 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 35 °F, low 16 °F 35°16° JanFebruary: average high 40 °F, low 19 °F 40°19° FebMarch: average high 52 °F, low 28 °F 52°28° MarApril: average high 65 °F, low 38 °F 65°38° AprMay: average high 76 °F, low 49 °F 76°49° MayJune: average high 85 °F, low 60 °F 85°60° JunJuly: average high 88 °F, low 63 °F 88°63° JulAugust: average high 85 °F, low 60 °F 85°60° AugSeptember: average high 80 °F, low 52 °F 80°52° SepOctober: average high 68 °F, low 42 °F 68°42° OctNovember: average high 53 °F, low 31 °F 53°31° NovDecember: average high 40 °F, low 22 °F 40°22° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.13 in precipitation 2.1 JanFebruary: 2.07 in precipitation 2.1 FebMarch: 2.47 in precipitation 2.5 MarApril: 3.77 in precipitation 3.8 AprMay: 4.81 in precipitation 4.8 MayJune: 4.81 in precipitation 4.8 JunJuly: 4.74 in precipitation 4.7 JulAugust: 4.00 in precipitation 4.0 AugSeptember: 3.16 in precipitation 3.2 SepOctober: 3.32 in precipitation 3.3 OctNovember: 2.73 in precipitation 2.7 NovDecember: 2.11 in precipitation 2.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Piper City, IL (11 mi away); precipitation: Watseka 6.9 Wnw, IL (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

4 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

609385b
Gilman, IL · 4 mi
609285b
Crescent City, IL · 7 mi
609686a
Thawville, IL · 8 mi
609186a
Buckley, IL · 8 mi
609305b
Danforth, IL · 9 mi
609246a
Cissna Park, IL · 11 mi
609115b
Ashkum, IL · 12 mi
609596a
Piper City, IL · 12 mi

Illinois planting zones →

Questions about 60955

What planting zone is ZIP code 60955?

ZIP code 60955 (Onarga, IL) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Onarga, IL?

The median last spring frost (32 °F) near 60955 is April 25; after May 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Piper City station.

When is the first frost in Onarga, IL?

The median first fall frost near 60955 is October 20, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 60955?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 60955 get?

About 40.1 inches of precipitation a year (NOAA 1991–2020 normals, Watseka 6.9 Wnw station).

How hot do summers get in Onarga, IL?

The average high peaks at 88 °F in July, with about 28 days a year at 90 °F or more.

What kind of soil does 60955 have?

The USDA soil survey maps Sawmill at the center of ZIP 60955: silty clay loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Onarga, IL in 2026?

Spring leaf-out near 60955 came on Mar 15 in 2026, 17 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Onarga, IL?

Long-day onions: the longest day near 60955 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).