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

Planting zone for 98295 — Sumas, WA

ZIP code 98295 (Sumas, Whatcom County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is April 18 and the first fall frost October 18.

Where ZIP 98295 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.

Zone8a10 to 15 °F
Coldest night−12.2 to −9.4 °C
Last frostApr 18
First frostOct 18
2012 zone8a

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 8a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sumas, WA…

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 Sumas, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 18median — 50% chance of a later frost
Safe for tender plantsMay 5only 10% chance of frost after
First fall frostOctober 18median — 10% chance by Sep 28
Growing season185 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 18 and returns around November 7.

From the NOAA station Clearbrook, WA — 6 miles away, elevation 66 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 98295

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 7 – Mar 21
SpinachSow outdoors · Mar 7 – Mar 28
Broccoli, cabbageStart indoors · Feb 7 – Feb 21
Broccoli, cabbageTransplant · Mar 28 – Apr 11
Onion setsPlant outdoors · Mar 21 – Apr 4
PotatoesPlant outdoors · Mar 28 – Apr 11
LettuceSow outdoors · Mar 21 – Apr 4
Carrots, beetsSow outdoors · Mar 28 – Apr 11
TomatoesStart indoors · Feb 21 – Mar 7
TomatoesTransplant · Apr 25 – May 9
Peppers, eggplantStart indoors · Feb 7 – Feb 21
Peppers, eggplantTransplant · May 2 – May 16
BeansSow outdoors · Apr 25 – May 9
Sweet cornSow outdoors · Apr 25 – May 9
Cucumbers, squashSow outdoors · Apr 25 – May 9
Fall lettuce, spinachSow outdoors · Aug 23 – Sep 6
GarlicPlant cloves · Oct 4 – Nov 8
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 18) 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 98295 came on Mar 9 — 9 days later than the 1991–2020 average (Feb 28).

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 Sumas, WA

The soil mapped at the center of ZIP 98295 is Briscot — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter6%high
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if drainedUSDA classification

Map unit: Briscot silt loam, drained, 0 to 2 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 98295; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sumas, WA

Summer high77 °Faverage high, August
Winter low32 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights57nights a year at 32 °F or less
Growing degree days1,712base 50 °F — the season’s usable heat
Longest day16 h 12 mindaylight on June 21
Shortest day8 h 13 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation49.9 inper year, rain and melted snow
Snowfall11 inper year

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 44 °F, low 32 °F 44°32° JanFebruary: average high 48 °F, low 33 °F 48°33° FebMarch: average high 53 °F, low 36 °F 53°36° MarApril: average high 59 °F, low 39 °F 59°39° AprMay: average high 66 °F, low 45 °F 66°45° MayJune: average high 70 °F, low 49 °F 70°49° JunJuly: average high 76 °F, low 51 °F 76°51° JulAugust: average high 77 °F, low 50 °F 77°50° AugSeptember: average high 71 °F, low 47 °F 71°47° SepOctober: average high 59 °F, low 42 °F 59°42° OctNovember: average high 49 °F, low 36 °F 49°36° NovDecember: average high 43 °F, low 32 °F 43°32° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″8″January: 6.98 in precipitation, 3.1 in snowfall 7.0❄3 JanFebruary: 3.85 in precipitation, 2.7 in snowfall 3.9❄3 FebMarch: 5.00 in precipitation, 1 in snowfall 5.0❄1 MarApril: 3.97 in precipitation, 0.1 in snowfall 4.0 AprMay: 3.17 in precipitation 3.2 MayJune: 2.39 in precipitation 2.4 JunJuly: 1.45 in precipitation 1.4 JulAugust: 1.50 in precipitation 1.5 AugSeptember: 2.93 in precipitation 2.9 SepOctober: 5.31 in precipitation 5.3 OctNovember: 7.11 in precipitation, 1.3 in snowfall 7.1❄1 NovDecember: 6.19 in precipitation, 2.6 in snowfall 6.2❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Clearbrook, WA (6 mi away); precipitation: Clearbrook, WA (6 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.

982768a
Nooksack, WA · 7 mi
982668a
Maple Falls, WA · 7 mi
982478a
Everson, WA · 8 mi
982648a
Lynden, WA · 12 mi
982268a
Bellingham, WA · 17 mi
982448a
Deming, WA · 20 mi
982278b
Bellingham, WA · 20 mi
982288b
Bellingham, WA · 20 mi

Washington planting zones →

Questions about 98295

What planting zone is ZIP code 98295?

ZIP code 98295 (Sumas, WA) is in USDA hardiness zone 8a on the 2023 map: the coldest night of an average winter reaches 10 to 15 °F (−12.2 to −9.4 °C).

When is the last frost in Sumas, WA?

The median last spring frost (32 °F) near 98295 is April 18; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Clearbrook station.

When is the first frost in Sumas, WA?

The median first fall frost near 98295 is October 18, giving a median frost-free growing season of 185 days.

When should I plant tomatoes in 98295?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 98295 get?

About 49.9 inches of precipitation a year and 11 inches of snowfall (NOAA 1991–2020 normals, Clearbrook station).

How hot do summers get in Sumas, WA?

The average high peaks at 77 °F in August, with about 2 days a year at 90 °F or more.

What kind of soil does 98295 have?

The USDA soil survey maps Briscot at the center of ZIP 98295: silt loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Sumas, WA in 2026?

Spring leaf-out near 98295 came on Mar 9 in 2026, 9 days later than the 1991–2020 average (Feb 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sumas, WA?

Long-day onions: the longest day near 98295 is 16 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).