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

Planting zone for 52731 — Charlotte, IA

ZIP code 52731 (Charlotte, Clinton County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 25 and the first fall frost October 14.

Where ZIP 52731 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.

Zone5a−20 to −15 °F
Coldest night−28.9 to −26.1 °C
Last frostApr 25
First frostOct 14
2012 zone5a

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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Charlotte, IA…

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 Charlotte, IA

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 9only 10% chance of frost after
First fall frostOctober 14median — 10% chance by Sep 30
Growing season171 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around October 24.

From the NOAA station Maquoketa, IA — 12 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 52731

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 19 – Sep 2
GarlicPlant cloves · Sep 30 – Nov 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 14) 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 52731 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 5a in Iowa

461 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. Each links to its USDA PLANTS profile.

Trees 46

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °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 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °F

Shrubs 77

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 hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 185

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 133

arctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fblue grama1 ft · blooms early summer · high shade tolerance · to −43 °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 Charlotte, IA.

Soil in Charlotte, IA

The soil mapped at the center of ZIP 52731 is Burkhardt — sandy loam, excessively drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageExcessively drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Burkhardt sandy loam, 14 to 25 percent slopes, moderately erode.

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 52731; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Charlotte, IA

Summer high82 °Faverage high, July
Winter low11 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights153nights a year at 32 °F or less
Growing degree days2,902base 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)
Precipitation39 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 27 °F, low 11 °F 27°11° JanFebruary: average high 31 °F, low 15 °F 31°15° FebMarch: average high 45 °F, low 26 °F 45°26° MarApril: average high 59 °F, low 37 °F 59°37° AprMay: average high 70 °F, low 49 °F 70°49° MayJune: average high 79 °F, low 60 °F 79°60° JunJuly: average high 82 °F, low 63 °F 82°63° JulAugust: average high 81 °F, low 61 °F 81°61° AugSeptember: average high 75 °F, low 52 °F 75°52° SepOctober: average high 62 °F, low 40 °F 62°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

0″1″2″3″4″5″January: 1.50 in precipitation 1.5 JanFebruary: 1.59 in precipitation 1.6 FebMarch: 2.50 in precipitation 2.5 MarApril: 3.86 in precipitation 3.9 AprMay: 4.80 in precipitation 4.8 MayJune: 4.93 in precipitation 4.9 JunJuly: 4.23 in precipitation 4.2 JulAugust: 4.58 in precipitation 4.6 AugSeptember: 3.71 in precipitation 3.7 SepOctober: 2.98 in precipitation 3.0 OctNovember: 2.36 in precipitation 2.4 NovDecember: 1.96 in precipitation 2.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Maquoketa, IA (12 mi away); precipitation: De Witt 1.4 Wnw, IA (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

527505a
Goose Lake, IA · 5 mi
527745b
Welton, IA · 7 mi
520695a
Preston, IA · 7 mi
520375a
Delmar, IA · 8 mi
527275a
Bryant, IA · 8 mi
527425b
De Witt, IA · 9 mi
520745a
Spragueville, IA · 10 mi
527015a
Andover, IA · 12 mi

Iowa planting zones →

Questions about 52731

What planting zone is ZIP code 52731?

ZIP code 52731 (Charlotte, IA) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Charlotte, IA?

The median last spring frost (32 °F) near 52731 is April 25; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Maquoketa station.

When is the first frost in Charlotte, IA?

The median first fall frost near 52731 is October 14, giving a median frost-free growing season of 171 days.

When should I plant tomatoes in 52731?

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 52731 get?

About 39 inches of precipitation a year (NOAA 1991–2020 normals, De Witt 1.4 Wnw station).

How hot do summers get in Charlotte, IA?

The average high peaks at 82 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 52731 have?

The USDA soil survey maps Burkhardt at the center of ZIP 52731: sandy loam, excessively drained, pH about 6.2 (slightly acidic).

Did spring come early in Charlotte, IA in 2026?

Spring leaf-out near 52731 came on Mar 25 in 2026, 14 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Charlotte, IA?

Long-day onions: the longest day near 52731 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).