Location of County of Warner in Alberta — County of Warner within Alberta

Hardiness Zone in County of Warner

County of Warner is generally treated as Canadian plant hardiness zone 4a, with a frost-free window on the order of 125 days. The zone is read from the Natural Resources Canada plant hardiness map (4th edition, 1991–2020 normals) at a representative quarter; frost dates are a regional table keyed by zone, not a logger on your fence. Those two numbers decide more tree deaths than soil tests do.

Zone 4a with about 125 frost-free days and high heat units. Chinooks make winter unpredictable for perennials.

What the zone is — and is not

Agriculture and Agri-Food Canada’s plant hardiness maps combine several climate variables, not just one winter low. A zone 4a label means a typical winter in this belt, not the worst winter of the decade, and not the frost pocket at the bottom of your driveway.

Use it to:

Filter nursery stock (do not buy zone 5 peaches for a County of Warner field)
Plan shelterbelts that will still be standing in twenty years
Time cover crops against a 125-day window

Do not use it to:

Ignore a north-facing draw
Skip a thermometer logger for one season
Assume the town of Milk River and a rural quarter share the same last frost

Frost-free days in practice

125 days is a regional sketch. Last spring frost and first fall frost move with elevation, wet ground, and cold-air drainage. In County of Warner, watch:

River and lake edges that radiate heat at night — or collect cold
Open peat or muskeg that frosts early
South walls and gravel pads that buy you a week

A food forest that needs 130 days will fight this county most years. A shelterbelt of zone 4a natives will not.

Pair climate with water and sun

Zone is only one pillar. A 4a site with a 60 m well and 1.1 kWh/m²/day in winter is a different homestead than the same zone on a municipal line. Plan trees, wells, and panels on the same map.

Flood or wet ground near Milk River valley, Verdigris Lake lowlands, Writing-on-Stone coulees can also shorten the effective season by keeping soils cold in May.

See this for your specific parcel

Generate a free land report for a property in County of Warner →

Sampled data for County of Warner

From a Land Intelligence report run on a representative quarter in Township 5, Range 19, W4. These are measured or record-based values for that location, shown to put the county figures above in context. They are not your parcel.

Annual mean7.8 °Clow -24.7 °C · high 36.1 °C in the sampled year

Days with frost128in the sampled year

Frost windowMay 12 – Sep 20regional table for zone 4a

Growing degree days2037base 5 °C

Precipitation380 mm/yr30-year normal at the sample point

Open-Meteo daily archive (ERA5 reanalysis), 2025-10-09 to 2026-10-09: one recent year at the sample point, not a 30-year normal. Use it for the shape of the year, not for a design value.

Growing zones near County of Warner: Lethbridge (zone 4b) · Taber (zone 4a) · Cardston (zone 4b) · Alberta growing zones map

Neighbouring counties: Lethbridge County (46 km) · MD of Taber (55 km) · Cardston County (64 km) · County of Forty Mile (88 km) · Compare County of Warner with another county

Sampled from the live report pipeline at a representative quarter in Township 5, Range 19, W4 on 2026-10-08: hardiness zone, solar irradiance (18 well records within 5 km). Kept as regional estimates: well depth (only 18 nearby records at the sample point). Text reviewed 2026-10-09. Methodology.

Common questions

What should I plant in County of Warner?

Start with zone 4a stock and a 125-day season. Then walk frost pockets.

Is the town of Milk River the same zone?

Often close, not identical. Elevation and cold-air drainage on a rural lot can run colder than town.