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

Planting zone for 61911 — Arthur, IL

ZIP code 61911 (Arthur, Douglas County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 15 and the first fall frost October 20.

Where ZIP 61911 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 15
First frostOct 20
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 Arthur, 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 Arthur, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 15median — 50% chance of a later frost
Safe for tender plantsMay 1only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 7
Growing season188 daysfrost-free, median

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

From the NOAA station Tuscola, IL — 11 miles away, elevation 650 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 61911

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 4 – Mar 18
SpinachSow outdoors · Mar 4 – Mar 25
Broccoli, cabbageStart indoors · Feb 4 – Feb 18
Broccoli, cabbageTransplant · Mar 25 – Apr 8
Onion setsPlant outdoors · Mar 18 – Apr 1
PotatoesPlant outdoors · Mar 25 – Apr 8
LettuceSow outdoors · Mar 18 – Apr 1
Carrots, beetsSow outdoors · Mar 25 – Apr 8
TomatoesStart indoors · Feb 18 – Mar 4
TomatoesTransplant · Apr 22 – May 6
Peppers, eggplantStart indoors · Feb 4 – Feb 18
Peppers, eggplantTransplant · Apr 29 – May 13
BeansSow outdoors · Apr 22 – May 6
Sweet cornSow outdoors · Apr 22 – May 6
Cucumbers, squashSow outdoors · Apr 22 – May 6
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 15) 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 61911 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 Arthur, IL.

Soil in Arthur, IL

The soil mapped at the center of ZIP 61911 is Drummer — 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 matter5.5%high
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Drummer-Milford silty clay loams, 0 to 2 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 61911; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Arthur, IL

Summer high85 °Faverage high, July
Winter low18 °Faverage low, January
Hot days27days a year at 90 °F or more
Freezing nights117nights a year at 32 °F or less
Growing degree days3,578base 50 °F — the season’s usable heat
Longest day14 h 59 mindaylight on June 21
Shortest day9 h 21 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation40.1 inper year, rain and melted snow
Snowfall15 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 18 °F 34°18° JanFebruary: average high 39 °F, low 21 °F 39°21° FebMarch: average high 50 °F, low 31 °F 50°31° MarApril: average high 64 °F, low 42 °F 64°42° AprMay: average high 74 °F, low 53 °F 74°53° MayJune: average high 82 °F, low 63 °F 82°63° JunJuly: average high 85 °F, low 65 °F 85°65° JulAugust: average high 84 °F, low 63 °F 84°63° AugSeptember: average high 79 °F, low 55 °F 79°55° SepOctober: average high 66 °F, low 43 °F 66°43° OctNovember: average high 51 °F, low 32 °F 51°32° NovDecember: average high 39 °F, low 24 °F 39°24° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.44 in precipitation, 4 in snowfall 2.4❄4 JanFebruary: 2.01 in precipitation, 4.3 in snowfall 2.0❄4 FebMarch: 2.76 in precipitation, 1.3 in snowfall 2.8❄1 MarApril: 4.11 in precipitation, 0.3 in snowfall 4.1 AprMay: 4.88 in precipitation 4.9 MayJune: 4.46 in precipitation 4.5 JunJuly: 4.16 in precipitation 4.2 JulAugust: 2.69 in precipitation 2.7 AugSeptember: 3.30 in precipitation 3.3 SepOctober: 3.55 in precipitation 3.5 OctNovember: 3.24 in precipitation, 0.5 in snowfall 3.2❄1 NovDecember: 2.52 in precipitation, 4.7 in snowfall 2.5❄5 Dec

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

619136a
Atwood, IL · 9 mi
619106a
Arcola, IL · 9 mi
619316a
Humboldt, IL · 10 mi
619516a
Sullivan, IL · 10 mi
619376a
Lovington, IL · 10 mi
619536a
Tuscola, IL · 12 mi
619296a
Hammond, IL · 12 mi
618136a
Bement, IL · 15 mi

Illinois planting zones →

Questions about 61911

What planting zone is ZIP code 61911?

ZIP code 61911 (Arthur, 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 Arthur, IL?

The median last spring frost (32 °F) near 61911 is April 15; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Tuscola station.

When is the first frost in Arthur, IL?

The median first fall frost near 61911 is October 20, giving a median frost-free growing season of 188 days.

When should I plant tomatoes in 61911?

Start tomato seeds indoors around Feb 18 – Mar 4 and set transplants outside around Apr 22 – May 6, one to three weeks after the median last frost.

How much rain and snow does 61911 get?

About 40.1 inches of precipitation a year and 15 inches of snowfall (NOAA 1991–2020 normals, Lovington station).

How hot do summers get in Arthur, IL?

The average high peaks at 85 °F in July, with about 27 days a year at 90 °F or more.

What kind of soil does 61911 have?

The USDA soil survey maps Drummer at the center of ZIP 61911: silty clay loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Arthur, IL in 2026?

Spring leaf-out near 61911 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 Arthur, IL?

Intermediate onions: the longest day near 61911 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.