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

Planting zone for 61342 — Mendota, IL

ZIP code 61342 (Mendota, LaSalle County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 27 and the first fall frost October 15.

Where ZIP 61342 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 27
First frostOct 15
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 Mendota, 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 Mendota, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 27median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 15median — 10% chance by Sep 30
Growing season171 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 15 and returns around October 25.

From the NOAA station Paw Paw 2s, IL — 10 miles away, elevation 889 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 61342

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 16 – Mar 30
SpinachSow outdoors · Mar 16 – Apr 6
Broccoli, cabbageStart indoors · Feb 16 – Mar 2
Broccoli, cabbageTransplant · Apr 6 – Apr 20
Onion setsPlant outdoors · Mar 30 – Apr 13
PotatoesPlant outdoors · Apr 6 – Apr 20
LettuceSow outdoors · Mar 30 – Apr 13
Carrots, beetsSow outdoors · Apr 6 – Apr 20
TomatoesStart indoors · Mar 2 – Mar 16
TomatoesTransplant · May 4 – May 18
Peppers, eggplantStart indoors · Feb 16 – Mar 2
Peppers, eggplantTransplant · May 11 – May 25
BeansSow outdoors · May 4 – May 18
Sweet cornSow outdoors · May 4 – May 18
Cucumbers, squashSow outdoors · May 4 – May 18
Fall lettuce, spinachSow outdoors · Aug 20 – Sep 3
GarlicPlant cloves · Oct 1 – Nov 5
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 15) 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 61342 came on Mar 21 — 16 days earlier than the 1991–2020 average (Apr 6).

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 Mendota, IL

The soil mapped at the center of ZIP 61342 is Spaulding — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH7.9alkaline; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter5%high
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Spaulding silty clay loam, 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 61342; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mendota, IL

Summer high82 °Faverage high, July
Winter low12 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights148nights a year at 32 °F or less
Growing degree days2,824base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.4 inper year, rain and melted snow
Snowfall25 inper year

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 28 °F, low 12 °F 28°12° JanFebruary: average high 32 °F, low 16 °F 32°16° FebMarch: average high 45 °F, low 26 °F 45°26° MarApril: average high 59 °F, low 36 °F 59°36° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 82 °F, low 62 °F 82°62° JulAugust: average high 80 °F, low 60 °F 80°60° AugSeptember: average high 75 °F, low 52 °F 75°52° SepOctober: average high 63 °F, low 40 °F 63°40° OctNovember: average high 46 °F, low 28 °F 46°28° NovDecember: average high 33 °F, low 18 °F 33°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 1.85 in precipitation, 7.3 in snowfall 1.9❄7 JanFebruary: 1.67 in precipitation, 7.6 in snowfall 1.7❄8 FebMarch: 2.23 in precipitation, 3 in snowfall 2.2❄3 MarApril: 3.63 in precipitation, 0.3 in snowfall 3.6 AprMay: 4.77 in precipitation 4.8 MayJune: 5.36 in precipitation 5.4 JunJuly: 4.36 in precipitation 4.4 JulAugust: 3.81 in precipitation 3.8 AugSeptember: 3.29 in precipitation 3.3 SepOctober: 3.07 in precipitation 3.1 OctNovember: 2.36 in precipitation, 0.8 in snowfall 2.4❄1 NovDecember: 1.98 in precipitation, 6.3 in snowfall 2.0❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Paw Paw 2s, IL (10 mi away); precipitation: Mendota 2 Se, IL (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

613725b
Troy Grove, IL · 5 mi
605185b
Earlville, IL · 9 mi
613305b
La Moille, IL · 10 mi
613175b
Cherry, IL · 10 mi
613015b
La Salle, IL · 10 mi
613735b
Utica, IL · 10 mi
613125b
Arlington, IL · 11 mi
613675b
Sublette, IL · 11 mi

Illinois planting zones →

Questions about 61342

What planting zone is ZIP code 61342?

ZIP code 61342 (Mendota, 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 Mendota, IL?

The median last spring frost (32 °F) near 61342 is April 27; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Paw Paw 2s station.

When is the first frost in Mendota, IL?

The median first fall frost near 61342 is October 15, giving a median frost-free growing season of 171 days.

When should I plant tomatoes in 61342?

Start tomato seeds indoors around Mar 2 – Mar 16 and set transplants outside around May 4 – May 18, one to three weeks after the median last frost.

How much rain and snow does 61342 get?

About 38.4 inches of precipitation a year and 25 inches of snowfall (NOAA 1991–2020 normals, Mendota 2 Se station).

How hot do summers get in Mendota, IL?

The average high peaks at 82 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 61342 have?

The USDA soil survey maps Spaulding at the center of ZIP 61342: silty clay loam, poorly drained, pH about 7.9 (alkaline).

Did spring come early in Mendota, IL in 2026?

Spring leaf-out near 61342 came on Mar 21 in 2026, 16 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mendota, IL?

Long-day onions: the longest day near 61342 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).