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

Planting zone for 49781 — Saint Ignace, MI

ZIP code 49781 (Saint Ignace, Mackinac County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 23 and the first fall frost September 30.

Where ZIP 49781 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 23

First frostSep 30

2012 zone5a

Was 5a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Saint Ignace, MI…

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 Ignace, MI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 23median — 50% chance of a later frost

Safe for tender plantsJune 6only 10% chance of frost after

First fall frostSeptember 30median — 10% chance by Sep 15

Growing season130 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 13.

From the NOAA station Moran, MI — 4 miles away, elevation 696 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 49781

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 11 – Apr 25

SpinachSow outdoors · Apr 11 – May 2

Broccoli, cabbageStart indoors · Mar 14 – Mar 28

Broccoli, cabbageTransplant · May 2 – May 16

Onion setsPlant outdoors · Apr 25 – May 9

PotatoesPlant outdoors · May 2 – May 16

LettuceSow outdoors · Apr 25 – May 9

Carrots, beetsSow outdoors · May 2 – May 16

TomatoesStart indoors · Mar 28 – Apr 11

TomatoesTransplant · May 30 – Jun 13

Peppers, eggplantStart indoors · Mar 14 – Mar 28

Peppers, eggplantTransplant · Jun 6 – Jun 20

BeansSow outdoors · May 30 – Jun 13

Sweet cornSow outdoors · May 30 – Jun 13

Cucumbers, squashSow outdoors · May 30 – Jun 13

Fall lettuce, spinachSow outdoors · Aug 5 – Aug 19

GarlicPlant cloves · Sep 16 – Oct 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 23) and first fall frost (Sep 30) 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 49781 came on May 5 — 4 days later than the 1991–2020 average (May 1).

average
May 12026
May 5

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 Michigan

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

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 Ignace, MI.

Soil in Saint Ignace, MI

The soil mapped at the center of ZIP 49781 is Eastport — slightly decomposed plant material, excessively drained.

TextureSlightly decomposed plant materialtop layer

pH4.0strongly acidic; most vegetables like 6.0–7.0

DrainageExcessively drainednatural drainage class

Organic matter75%high

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Eastport-Leafriver complex, 0 to 35 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 49781; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Ignace, MI

Summer high77 °Faverage high, July

Winter low7 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights182nights a year at 32 °F or less

Growing degree days1,641base 50 °F — the season’s usable heat

Longest day15 h 45 mindaylight on June 21

Shortest day8 h 39 mindaylight on December 21

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

Precipitation35 inper year, rain and melted snow

Snowfall81 inper year; 127 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: Moran, MI (4 mi away); precipitation: Moran, MI (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.

497605a

Moran, MI · 8 mi

497575b

Mackinac Island, MI · 9 mi

497455a

Hessel, MI · 12 mi

497015b

Mackinaw City, MI · 14 mi

497185b

Carp Lake, MI · 16 mi

Trout Lake, MI · 23 mi

Michigan planting zones →

Questions about 49781

What planting zone is ZIP code 49781?

ZIP code 49781 (Saint Ignace, MI) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Saint Ignace, MI?

The median last spring frost (32 °F) near 49781 is May 23; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Moran station.

When is the first frost in Saint Ignace, MI?

The median first fall frost near 49781 is September 30, giving a median frost-free growing season of 130 days.

When should I plant tomatoes in 49781?

Start tomato seeds indoors around Mar 28 – Apr 11 and set transplants outside around May 30 – Jun 13, one to three weeks after the median last frost.

How much rain and snow does 49781 get?

About 35 inches of precipitation a year and 81 inches of snowfall (NOAA 1991–2020 normals, Moran station).

How hot do summers get in Saint Ignace, MI?

The average high peaks at 77 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 49781 have?

The USDA soil survey maps Eastport at the center of ZIP 49781: slightly decomposed plant material, excessively drained, pH about 4.0 (strongly acidic).

Did spring come early in Saint Ignace, MI in 2026?

Spring leaf-out near 49781 came on May 5 in 2026, 4 days later than the 1991–2020 average (May 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Ignace, MI?

Long-day onions: the longest day near 49781 is 15 h 45 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 49781 change?

Yes. The 2012 USDA map put 49781 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.