Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 52041 — Earlville, IA

ZIP code 52041 (Earlville, Delaware County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 3 and the first fall frost October 4.

Where ZIP 52041 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 frostMay 3

First frostOct 4

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 Earlville, 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 Earlville, IA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 3median — 50% chance of a later frost

Safe for tender plantsMay 16only 10% chance of frost after

First fall frostOctober 4median — 10% chance by Sep 22

Growing season154 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 15.

From the NOAA station Manchester #2, IA — 11 miles away, elevation 991 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 52041

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 22 – Apr 5

SpinachSow outdoors · Mar 22 – Apr 12

Broccoli, cabbageStart indoors · Feb 22 – Mar 8

Broccoli, cabbageTransplant · Apr 12 – Apr 26

Onion setsPlant outdoors · Apr 5 – Apr 19

PotatoesPlant outdoors · Apr 12 – Apr 26

LettuceSow outdoors · Apr 5 – Apr 19

Carrots, beetsSow outdoors · Apr 12 – Apr 26

TomatoesStart indoors · Mar 8 – Mar 22

TomatoesTransplant · May 10 – May 24

Peppers, eggplantStart indoors · Feb 22 – Mar 8

Peppers, eggplantTransplant · May 17 – May 31

BeansSow outdoors · May 10 – May 24

Sweet cornSow outdoors · May 10 – May 24

Cucumbers, squashSow outdoors · May 10 – May 24

Fall lettuce, spinachSow outdoors · Aug 9 – Aug 23

GarlicPlant cloves · Sep 20 – Oct 25

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 4) 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 52041 came on Mar 25 — 18 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
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).

Soil in Earlville, IA

The soil mapped at the center of ZIP 52041 is Backbone — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH6.8neutral; 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: Backbone fine sandy loam, 5 to 9 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 52041; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Earlville, IA

Summer high82 °Faverage high, July

Winter low8 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights158nights a year at 32 °F or less

Growing degree days2,660base 50 °F — the season’s usable heat

Longest day15 h 18 mindaylight on June 21

Shortest day9 h 03 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation38.6 inper year, rain and melted snow

Snowfall35 inper year; 66 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Manchester #2, IA (11 mi away); precipitation: Manchester #2, 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.

520364b

Delaware, IA · 5 mi

520405a

Dyersville, IA · 6 mi

New Vienna, IA · 9 mi

520575a

Manchester, IA · 10 mi

520785a

Worthington, IA · 10 mi

522375a

Hopkinton, IA · 11 mi

Iowa planting zones →

Questions about 52041

What planting zone is ZIP code 52041?

ZIP code 52041 (Earlville, 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 Earlville, IA?

The median last spring frost (32 °F) near 52041 is May 3; after May 16 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Manchester #2 station.

When is the first frost in Earlville, IA?

The median first fall frost near 52041 is October 4, giving a median frost-free growing season of 154 days.

When should I plant tomatoes in 52041?

Start tomato seeds indoors around Mar 8 – Mar 22 and set transplants outside around May 10 – May 24, one to three weeks after the median last frost.

How much rain and snow does 52041 get?

About 38.6 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Manchester #2 station).

How hot do summers get in Earlville, IA?

The average high peaks at 82 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 52041 have?

The USDA soil survey maps Backbone at the center of ZIP 52041: fine sandy loam, well drained, pH about 6.8 (neutral).

Did spring come early in Earlville, IA in 2026?

Spring leaf-out near 52041 came on Mar 25 in 2026, 18 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Earlville, IA?

Long-day onions: the longest day near 52041 is 15 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).