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

Planting zone for 61489 — Williamsfield, IL

ZIP code 61489 (Williamsfield, Knox County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 21 and the first fall frost October 20.

Where ZIP 61489 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 21
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 Williamsfield, 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 Williamsfield, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 21median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 7
Growing season181 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around October 29.

From the NOAA station Knoxville, IL — 14 miles away, elevation 728 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 61489

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 10 – Mar 24
SpinachSow outdoors · Mar 10 – Mar 31
Broccoli, cabbageStart indoors · Feb 10 – Feb 24
Broccoli, cabbageTransplant · Mar 31 – Apr 14
Onion setsPlant outdoors · Mar 24 – Apr 7
PotatoesPlant outdoors · Mar 31 – Apr 14
LettuceSow outdoors · Mar 24 – Apr 7
Carrots, beetsSow outdoors · Mar 31 – Apr 14
TomatoesStart indoors · Feb 24 – Mar 10
TomatoesTransplant · Apr 28 – May 12
Peppers, eggplantStart indoors · Feb 10 – Feb 24
Peppers, eggplantTransplant · May 5 – May 19
BeansSow outdoors · Apr 28 – May 12
Sweet cornSow outdoors · Apr 28 – May 12
Cucumbers, squashSow outdoors · Apr 28 – May 12
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 21) 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 61489 came on Mar 11 — 22 days earlier than the 1991–2020 average (Apr 2).

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 Williamsfield, IL

The soil mapped at the center of ZIP 61489 is Rozetta — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Rozetta 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 61489; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Williamsfield, IL

Summer high84 °Faverage high, July
Winter low14 °Faverage low, January
Hot days13days a year at 90 °F or more
Freezing nights135nights a year at 32 °F or less
Growing degree days3,254base 50 °F — the season’s usable heat
Longest day15 h 07 mindaylight on June 21
Shortest day9 h 14 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation37.7 inper year, rain and melted snow
Snowfall21 inper year; 36 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 14 °F 32°14° JanFebruary: average high 36 °F, low 18 °F 36°18° FebMarch: average high 49 °F, low 29 °F 49°29° MarApril: average high 62 °F, low 39 °F 62°39° AprMay: average high 72 °F, low 51 °F 72°51° MayJune: average high 81 °F, low 61 °F 81°61° JunJuly: average high 84 °F, low 65 °F 84°65° JulAugust: average high 82 °F, low 63 °F 82°63° AugSeptember: average high 76 °F, low 54 °F 76°54° SepOctober: average high 64 °F, low 42 °F 64°42° OctNovember: average high 49 °F, low 31 °F 49°31° NovDecember: average high 36 °F, low 21 °F 36°21° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 1.98 in precipitation, 6 in snowfall 2.0❄6 JanFebruary: 1.94 in precipitation, 5.9 in snowfall 1.9❄6 FebMarch: 2.49 in precipitation, 2.8 in snowfall 2.5❄3 MarApril: 3.53 in precipitation, 0.4 in snowfall 3.5 AprMay: 4.65 in precipitation 4.7 MayJune: 4.36 in precipitation 4.4 JunJuly: 4.25 in precipitation 4.3 JulAugust: 3.65 in precipitation 3.6 AugSeptember: 3.95 in precipitation 4.0 SepOctober: 2.71 in precipitation, 0.1 in snowfall 2.7 OctNovember: 2.35 in precipitation, 0.7 in snowfall 2.4❄1 NovDecember: 1.88 in precipitation, 5.4 in snowfall 1.9❄5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Knoxville, IL (14 mi away); precipitation: Yates City, IL (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

614285b
Dahinda, IL · 4 mi
614515b
Laura, IL · 5 mi
614855b
Victoria, IL · 7 mi
615725b
Yates City, IL · 9 mi
614485b
Knoxville, IL · 11 mi
614365b
Gilson, IL · 11 mi
615295b
Elmwood, IL · 11 mi
614495b
La Fayette, IL · 12 mi

Illinois planting zones →

Questions about 61489

What planting zone is ZIP code 61489?

ZIP code 61489 (Williamsfield, 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 Williamsfield, IL?

The median last spring frost (32 °F) near 61489 is April 21; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Knoxville station.

When is the first frost in Williamsfield, IL?

The median first fall frost near 61489 is October 20, giving a median frost-free growing season of 181 days.

When should I plant tomatoes in 61489?

Start tomato seeds indoors around Feb 24 – Mar 10 and set transplants outside around Apr 28 – May 12, one to three weeks after the median last frost.

How much rain and snow does 61489 get?

About 37.7 inches of precipitation a year and 21 inches of snowfall (NOAA 1991–2020 normals, Yates City station).

How hot do summers get in Williamsfield, IL?

The average high peaks at 84 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 61489 have?

The USDA soil survey maps Rozetta at the center of ZIP 61489: silt loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Williamsfield, IL in 2026?

Spring leaf-out near 61489 came on Mar 11 in 2026, 22 days earlier than the 1991–2020 average (Apr 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Williamsfield, IL?

Long-day onions: the longest day near 61489 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).