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

Planting zone for 45646 — Latham, OH

ZIP code 45646 (Latham, Pike County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 21 and the first fall frost October 22.

Where ZIP 45646 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 21
First frostOct 22
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Latham, OH…

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 Latham, OH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 21median — 50% chance of a later frost
Safe for tender plantsMay 9only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 6
Growing season182 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around November 1.

From the NOAA station Waverly, OH — 19 miles away, elevation 571 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 45646

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 10 – Mar 24
SpinachSow outdoors · Mar 10 – Mar 31
Broccoli, cabbageStart indoors · Feb 10 – Feb 24
Broccoli, cabbageTransplant · Mar 31 – Apr 14
Onion setsPlant outdoors · Mar 24 – Apr 7
PotatoesPlant outdoors · Mar 31 – Apr 14
LettuceSow outdoors · Mar 24 – Apr 7
Carrots, beetsSow outdoors · Mar 31 – Apr 14
TomatoesStart indoors · Feb 24 – Mar 10
TomatoesTransplant · Apr 28 – May 12
Peppers, eggplantStart indoors · Feb 10 – Feb 24
Peppers, eggplantTransplant · May 5 – May 19
BeansSow outdoors · Apr 28 – May 12
Sweet cornSow outdoors · Apr 28 – May 12
Cucumbers, squashSow outdoors · Apr 28 – May 12
Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 21) and first fall frost (Oct 22) 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 45646 came on Mar 9 — 11 days earlier than the 1991–2020 average (Mar 20).

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 Latham, OH

The soil mapped at the center of ZIP 45646 is Trappist — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Trappist-Shelocta association, steep.

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 45646; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Latham, OH

Summer high86 °Faverage high, July
Winter low22 °Faverage low, January
Hot days26days a year at 90 °F or more
Freezing nights124nights a year at 32 °F or less
Growing degree days3,634base 50 °F — the season’s usable heat
Longest day14 h 55 mindaylight on June 21
Shortest day9 h 25 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation43.1 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 40 °F, low 22 °F 40°22° JanFebruary: average high 44 °F, low 24 °F 44°24° FebMarch: average high 54 °F, low 31 °F 54°31° MarApril: average high 66 °F, low 41 °F 66°41° AprMay: average high 75 °F, low 52 °F 75°52° MayJune: average high 83 °F, low 61 °F 83°61° JunJuly: average high 86 °F, low 65 °F 86°65° JulAugust: average high 85 °F, low 63 °F 85°63° AugSeptember: average high 80 °F, low 55 °F 80°55° SepOctober: average high 68 °F, low 43 °F 68°43° OctNovember: average high 55 °F, low 32 °F 55°32° NovDecember: average high 44 °F, low 27 °F 44°27° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.41 in precipitation 3.4 JanFebruary: 3.28 in precipitation 3.3 FebMarch: 4.05 in precipitation 4.0 MarApril: 3.99 in precipitation 4.0 AprMay: 4.31 in precipitation 4.3 MayJune: 4.02 in precipitation 4.0 JunJuly: 4.56 in precipitation 4.6 JulAugust: 3.05 in precipitation 3.0 AugSeptember: 3.04 in precipitation 3.0 SepOctober: 2.93 in precipitation 2.9 OctNovember: 2.81 in precipitation 2.8 NovDecember: 3.67 in precipitation 3.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Waverly, OH (19 mi away); precipitation: Piketon, OH (16 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

451726b
Sinking Spring, OH · 3 mi
456606b
Peebles, OH · 6 mi
456246b
Cynthiana, OH · 7 mi
456716b
Rarden, OH · 8 mi
456126b
Bainbridge, OH · 9 mi
456616b
Piketon, OH · 12 mi
451336b
Hillsboro, OH · 15 mi
456426b
Jasper, OH · 15 mi

Ohio planting zones →

Questions about 45646

What planting zone is ZIP code 45646?

ZIP code 45646 (Latham, OH) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Latham, OH?

The median last spring frost (32 °F) near 45646 is April 21; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Waverly station.

When is the first frost in Latham, OH?

The median first fall frost near 45646 is October 22, giving a median frost-free growing season of 182 days.

When should I plant tomatoes in 45646?

Start tomato seeds indoors around Feb 24 – Mar 10 and set transplants outside around Apr 28 – May 12, one to three weeks after the median last frost.

How much rain and snow does 45646 get?

About 43.1 inches of precipitation a year (NOAA 1991–2020 normals, Piketon station).

How hot do summers get in Latham, OH?

The average high peaks at 86 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 45646 have?

The USDA soil survey maps Trappist at the center of ZIP 45646: silt loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Latham, OH in 2026?

Spring leaf-out near 45646 came on Mar 9 in 2026, 11 days earlier than the 1991–2020 average (Mar 20), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Latham, OH?

Intermediate onions: the longest day near 45646 is 14 h 55 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 45646 change?

Yes. The 2012 USDA map put 45646 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.