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

Planting zone for 33037 — Key Largo, FL

ZIP code 33037 (Key Largo, Monroe County) is in USDA zone 11a: the coldest winter night averages 40 to 45 °F.

Where ZIP 33037 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.

Zone11a40 to 45 °F
Coldest night4.4 to 7.2 °C
Last frostrare
First frostrare
2012 zone11a

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 11a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Key Largo, FL…

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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station Royal Palm Rs, FL — 16 miles away, elevation 7 ft) the median growing season is 365 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 33037 came on Jan 11 — about the same time as the 1991–2020 average (Jan 10).

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 11a in Florida

518 plants native to the lower 48 states, recorded in Florida, and rated by the USDA to survive 40 °F or colder — the bottom of zone 11a. Each links to its USDA PLANTS profile.

Trees 72

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 °FAtlantic white cedar50 ft · blooms spring · medium shade tolerance · to −36 °F

Shrubs 134

aloe yucca15 ft · blooms early summer · medium shade tolerance · to −1 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °F

Wildflowers & perennials 154

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican century plant6 ft · blooms indeterminate · high shade tolerance · to 12 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °F

Grasses 138

American cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Fannual wildrice10 ft · blooms indeterminate · high shade tolerance · to 32 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °F

Vines 12

American wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °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 Key Largo, FL.

Soil in Key Largo, FL

The soil mapped at the center of ZIP 33037 is Keylargo — muck, very poorly drained.

TextureMucktop layer
DrainageVery poorly drainedconsider raised beds
Organic matter75%high
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Keylargo muck, tidal, 0 to 1 percent slopes, very frequently flooded.

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 33037; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Key Largo, FL

Summer high90 °Faverage high, July
Winter low63 °Faverage low, January
Hot days47days a year at 90 °F or more
Freezing nights0nights a year at 32 °F or less
Growing degree days10,139base 50 °F — the season’s usable heat
Longest day13 h 43 mindaylight on June 21
Shortest day10 h 34 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation57 inper year, rain and melted snow

Average high and low, by month

50°60°70°80°90°100°January: average high 76 °F, low 63 °F 76°63° JanFebruary: average high 78 °F, low 65 °F 78°65° FebMarch: average high 80 °F, low 67 °F 80°67° MarApril: average high 83 °F, low 71 °F 83°71° AprMay: average high 85 °F, low 74 °F 85°74° MayJune: average high 88 °F, low 77 °F 88°77° JunJuly: average high 90 °F, low 79 °F 90°79° JulAugust: average high 90 °F, low 79 °F 90°79° AugSeptember: average high 89 °F, low 78 °F 89°78° SepOctober: average high 86 °F, low 75 °F 86°75° OctNovember: average high 81 °F, low 70 °F 81°70° NovDecember: average high 78 °F, low 66 °F 78°66° Dec

Precipitation by month inches

0″2″4″6″8″January: 2.13 in precipitation 2.1 JanFebruary: 2.01 in precipitation 2.0 FebMarch: 2.22 in precipitation 2.2 MarApril: 3.33 in precipitation 3.3 AprMay: 4.76 in precipitation 4.8 MayJune: 7.91 in precipitation 7.9 JunJuly: 5.81 in precipitation 5.8 JulAugust: 6.89 in precipitation 6.9 AugSeptember: 8.18 in precipitation 8.2 SepOctober: 7.87 in precipitation 7.9 OctNovember: 3.31 in precipitation 3.3 NovDecember: 2.53 in precipitation 2.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: John Pennekamp Sp, FL (4 mi away); precipitation: John Pennekamp Sp, FL (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

3303511a
Homestead, FL · 14 mi
3307011b
Tavernier, FL · 16 mi
3303311a
Homestead, FL · 17 mi
3303010b
Homestead, FL · 19 mi
3303211a
Homestead, FL · 21 mi
3303110b
Homestead, FL · 21 mi
3317010b
Miami, FL · 23 mi
3309010b
Homestead, FL · 23 mi

Florida planting zones →

Questions about 33037

What planting zone is ZIP code 33037?

ZIP code 33037 (Key Largo, FL) is in USDA hardiness zone 11a on the 2023 map: the coldest night of an average winter reaches 40 to 45 °F (4.4 to 7.2 °C).

How much rain and snow does 33037 get?

About 57 inches of precipitation a year (NOAA 1991–2020 normals, John Pennekamp Sp station).

How hot do summers get in Key Largo, FL?

The average high peaks at 90 °F in July, with about 47 days a year at 90 °F or more.

What kind of soil does 33037 have?

The USDA soil survey maps Keylargo at the center of ZIP 33037: muck, very poorly drained.

Did spring come early in Key Largo, FL in 2026?

Spring leaf-out near 33037 came on Jan 11 in 2026, about the same as the 1991–2020 average (Jan 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Key Largo, FL?

Short-day onions: the longest day near 33037 is 13 h 43 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.