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

Planting zone for Dubuque, IA

Dubuque, IA is in USDA zone 5a across its 5 ZIP codes. The median last spring frost is April 19 and the first fall frost October 21.

Dubuque on the zone map

Outlined: its 3 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.

Zone5a−20 to −15 °F
ZIP codes5
Last frostApr 19
First frostOct 21
Growing season184 days

5a 5 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Dubuque, 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 Dubuque, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 19median — 50% chance of a later frost
Safe for tender plantsMay 4only 10% chance of frost after
First fall frostOctober 21median — 10% chance by Oct 7
Growing season184 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around November 1.

From the NOAA station Dubuque L&D 11, IA, elevation 620 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 Dubuque

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 8 – Mar 22
SpinachSow outdoors · Mar 8 – Mar 29
Broccoli, cabbageStart indoors · Feb 8 – Feb 22
Broccoli, cabbageTransplant · Mar 29 – Apr 12
Onion setsPlant outdoors · Mar 22 – Apr 5
PotatoesPlant outdoors · Mar 29 – Apr 12
LettuceSow outdoors · Mar 22 – Apr 5
Carrots, beetsSow outdoors · Mar 29 – Apr 12
TomatoesStart indoors · Feb 22 – Mar 8
TomatoesTransplant · Apr 26 – May 10
Peppers, eggplantStart indoors · Feb 8 – Feb 22
Peppers, eggplantTransplant · May 3 – May 17
BeansSow outdoors · Apr 26 – May 10
Sweet cornSow outdoors · Apr 26 – May 10
Cucumbers, squashSow outdoors · Apr 26 – May 10
Fall lettuce, spinachSow outdoors · Aug 26 – Sep 9
GarlicPlant cloves · Oct 7 – Nov 11
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 21) 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 52004 came on Mar 25 — 15 days earlier than the 1991–2020 average (Apr 9).

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 Dubuque, IA.

Soil in Dubuque, IA

The soil mapped at the center of ZIP 52004 is Lamont — fine sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

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

Map unit: Urban land-Lamont complex, 2 to 7 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 52004; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dubuque, IA

Summer high85 °Faverage high, July
Winter low10 °Faverage low, January
Hot days18days a year at 90 °F or more
Freezing nights133nights a year at 32 °F or less
Growing degree days3,078base 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)
Precipitation38.8 inper year, rain and melted snow
Snowfall36 inper year; 71 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 28 °F, low 10 °F 28°10° JanFebruary: average high 32 °F, low 13 °F 32°13° FebMarch: average high 45 °F, low 25 °F 45°25° MarApril: average high 59 °F, low 38 °F 59°38° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 81 °F, low 60 °F 81°60° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 82 °F, low 62 °F 82°62° AugSeptember: average high 75 °F, low 54 °F 75°54° SepOctober: average high 61 °F, low 42 °F 61°42° OctNovember: average high 46 °F, low 29 °F 46°29° NovDecember: average high 33 °F, low 18 °F 33°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 1.32 in precipitation, 11.7 in snowfall 1.3❄12 JanFebruary: 1.44 in precipitation, 8.6 in snowfall 1.4❄9 FebMarch: 2.10 in precipitation, 3.7 in snowfall 2.1❄4 MarApril: 3.77 in precipitation, 0.9 in snowfall 3.8❄1 AprMay: 4.44 in precipitation 4.4 MayJune: 5.64 in precipitation 5.6 JunJuly: 5.32 in precipitation 5.3 JulAugust: 3.75 in precipitation 3.8 AugSeptember: 3.88 in precipitation 3.9 SepOctober: 3.08 in precipitation, 0.1 in snowfall 3.1 OctNovember: 2.35 in precipitation, 1.2 in snowfall 2.4❄1 NovDecember: 1.74 in precipitation, 9.9 in snowfall 1.7❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dubuque L&D 11, IA (3 mi away); precipitation: Dubuque L&D 11, IA (3 mi away). Daylight is calculated from latitude.

ZIP codes in Dubuque

520015a
−20 to −15 °F
520025a
−20 to −15 °F
520035a
−20 to −15 °F
520045a
−20 to −15 °F
520995a
−20 to −15 °F

Iowa planting zones →

Questions about Dubuque

What planting zone is Dubuque, IA?

Dubuque, IA is in USDA hardiness zone 5a on the 2023 map (5a: −20 to −15 °F).

When is the last frost in Dubuque, IA?

The median last spring frost is April 19 and the median first fall frost is October 21 (NOAA 1991–2020 normals, Dubuque L&D 11 station).

When can I plant a garden in Dubuque, IA?

Cool-season crops like peas and spinach go in around Mar 8 – Mar 29; tomatoes, peppers, beans and squash after about Apr 26, once frost risk has passed.

What kind of onions grow in Dubuque, IA?

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

How much rain and snow does Dubuque, IA get?

About 38.8 inches of precipitation a year and 36 inches of snowfall (NOAA 1991–2020 normals).