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

Planting zone for Saint Charles, IL

Saint Charles, IL is in USDA zone 5b across its 2 ZIP codes. The median last spring frost is April 25 and the first fall frost October 19.

Saint Charles on the zone map

Outlined: its 2 ZIP code areas · 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
ZIP codes2
Last frostApr 25
First frostOct 19
Growing season174 days

5b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Saint Charles, 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 12only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 5
Growing season174 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around October 29.

From the NOAA station West Chicago Dupage Airport, IL, elevation 755 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 Saint Charles

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 24 – Sep 7
GarlicPlant cloves · Oct 5 – Nov 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 19) 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 60175 came on Mar 25 — 14 days earlier than the 1991–2020 average (Apr 8).

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 5b in Illinois

584 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 77

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 102

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 210

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 173

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 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °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 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Saint Charles, IL.

Soil in Saint Charles, IL

The soil mapped at the center of ZIP 60175 is Wingate — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH6.6neutral; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Wingate silt loam, cool mesic, 2 to 5 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 60175; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Charles, IL

Summer high84 °Faverage high, July
Winter low16 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights134nights a year at 32 °F or less
Growing degree days3,059base 50 °F — the season’s usable heat
Longest day15 h 14 mindaylight on June 21
Shortest day9 h 07 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.3 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 16 °F 31°16° JanFebruary: average high 35 °F, low 19 °F 35°19° FebMarch: average high 47 °F, low 28 °F 47°28° MarApril: average high 60 °F, low 38 °F 60°38° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 81 °F, low 59 °F 81°59° JunJuly: average high 84 °F, low 63 °F 84°63° JulAugust: average high 82 °F, low 62 °F 82°62° AugSeptember: average high 76 °F, low 54 °F 76°54° SepOctober: average high 62 °F, low 42 °F 62°42° OctNovember: average high 48 °F, low 31 °F 48°31° NovDecember: average high 35 °F, low 21 °F 35°21° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.78 in precipitation 1.8 JanFebruary: 1.78 in precipitation 1.8 FebMarch: 2.37 in precipitation 2.4 MarApril: 3.78 in precipitation 3.8 AprMay: 4.80 in precipitation 4.8 MayJune: 4.33 in precipitation 4.3 JunJuly: 3.88 in precipitation 3.9 JulAugust: 4.08 in precipitation 4.1 AugSeptember: 3.43 in precipitation 3.4 SepOctober: 3.33 in precipitation 3.3 OctNovember: 2.54 in precipitation 2.5 NovDecember: 2.15 in precipitation 2.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: West Chicago Dupage Airport, IL (7 mi away); precipitation: St. Charles 6.0 Nw, IL (2 mi away). Daylight is calculated from latitude.

ZIP codes in Saint Charles

601745b
−15 to −10 °F
601755b
−15 to −10 °F

Illinois planting zones →

Questions about Saint Charles

What planting zone is Saint Charles, IL?

Saint Charles, IL is in USDA hardiness zone 5b on the 2023 map (5b: −15 to −10 °F).

When is the last frost in Saint Charles, IL?

The median last spring frost is April 25 and the median first fall frost is October 19 (NOAA 1991–2020 normals, West Chicago Dupage Airport station).

When can I plant a garden in Saint Charles, IL?

Cool-season crops like peas and spinach go in around Mar 14 – Apr 4; tomatoes, peppers, beans and squash after about May 2, once frost risk has passed.

What kind of onions grow in Saint Charles, IL?

Long-day onions: the longest day is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Saint Charles, IL get?

About 38.3 inches of precipitation a year (NOAA 1991–2020 normals).