Photo: Doug Hay derivative work: MrPanyGoff · CC BY 2.0Few Canadian towns have milder winter nights than Duncan
In July the day’s top temperature is typically 22.7°C. The wettest month is January; the driest is July. Summers stay cool: July afternoons here are cooler than in 94% of Canadian towns. For walks and days out, the stretch from June to September brings highs of 20–23°C.
These are not Duncan’s own readings: ECCC keeps no normals there, so the page uses Victoria (Airport), 25 km south-east.
A year in Duncan at a glance
Each month’s typical high and low, in °C.
What stands out about Duncan’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in British Columbia beside it.
What a year in Duncan feels like
Seasons and months as ECCC’s 1991–2020 normals give them: a typical day’s high and low.
About 45 frosts and 83 warm days a year
Frost comes from November to April, most of all in January (about 10 nights).
Frost days by month
Average days at 0°C or below
Days above 20°C by month
Average days
901 mm of precipitation in a typical year
About 119 days a year bring 1 mm or more.
Rain and snow by month
Millimetres
Rain alone by month
Millimetres
About 39 cm of snow a year
Snow falls from November to March, most of all in December (about 12 cm).
Snowfall by month
Centimetres
Snow on the ground by month
Centimetres at month’s end
Heating a home in Duncan
84% of a year’s heating need falls between October and April. Months averaging under 10°C: November to April.
Heating degree days total each day’s gap between its mean temperature and 18°C. In heating terms, homes need less heating than 95% of Canadian towns.
Living with Duncan’s climate
Gardening, time outside, winter cold and summer heat, from the 1991–2020 normals.
Between the last frost, near 4 April, and the first, near 4 November, lie about 213 frost-free days.
The comfortable months for a day outside, highs of 17–27°C and nights of 8°C or more: Jun, Jul, Aug and Sep.
Parks & trails →Summer brings about 6 days when the humidex passes 30.
What averages leave out, the floods and ice storms, is on Duncan’s hazards page.
Flood & hazards →ECCC’s normals location: Victoria (Airport)
ECCC builds the Victoria (Airport) normals from 2 stations’ records over 1991–2020, joined where one replaced another.
| Distance from the town | 25 km south-east |
| Station altitude | 20 m |
| Completeness | meets the WMO “3 and 5” rule |
| WMO standard normals | No |
| Coldest reading, 1991–2020 | −10.5°C |
| Hottest reading, 1991–2020 | 36.3°C |
| Average wind | 9.7 km/h on average, most often from the west |
| Next-nearest location | Saturna CAPMON, 42 km |
How Duncan compares
Compared with 2,611 towns and neighbourhoods of 2,500 or more across Canada; the dots mark the other normals locations in British Columbia.
Nearby towns’ climate
Nearby places read from a different ECCC location (places on Duncan’s own would show the same figures). Distances here run 29–40 km: that is how far the nearest places with figures are from Duncan.
| Town | July high | January low | Rain & snow |
|---|---|---|---|
| Duncan Victoria (Airport) | 22.7°C | 1.6°C | 901 mm |
| Electoral Area H, Cowichan Valley 29 km · Vancouver International (Airport) | 22.4°C about the same | 1.4°C about the same | 1,160 mm |
| Southern Gulf Islands 30 km · Saturna CAPMON | 21.6°C 1.1°C cooler | 2.3°C 0.7°C milder | 802 mm |
| Langford 39 km · Victoria Gonzales (City) | 20.6°C 2.1°C cooler | 3.8°C 2.2°C milder | 675 mm |
Duncan weather by month
Month by month, 1991–2020: the usual high, low and mean, the rain and snow, and the snowfall.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | 7.5°C | 1.6°C | 4.6°C | 155 mm | 11 cm |
| February | 8.7°C | 1.4°C | 5.0°C | 85 mm | 7 cm |
| March | 10.8°C | 2.7°C | 6.8°C | 80 mm | 4 cm |
| April | 13.7°C | 4.6°C | 9.1°C | 48 mm | 1 cm |
| May | 17.5°C | 7.6°C | 12.6°C | 37 mm | 0 cm |
| June | 20.2°C | 10.1°C | 15.2°C | 29 mm | 0 cm |
| July | 22.7°C | 11.7°C | 17.2°C | 20 mm | 0 cm |
| August | 22.6°C | 11.6°C | 17.1°C | 24 mm | 0 cm |
| September | 19.7°C | 9.2°C | 14.5°C | 36 mm | 0 cm |
| October | 14.3°C | 6.0°C | 10.2°C | 96 mm | under 1 cm |
| November | 9.9°C | 3.0°C | 6.5°C | 146 mm | 4 cm |
| December | 7.3°C | 1.5°C | 4.4°C | 146 mm | 12 cm |
| Year | 14.6°C | 5.9°C | 10.3°C | 901 mm | 39 cm |
June: 2.1°C at its coldest, 33.5°C at its warmest
From one year to the next, February’s average typically shifts by 1.5°C around its normal of 5.0°C, the widest of any month, while August’s shifts by 0.7°C.
Where Duncan’s numbers come from
Averages over 30 years, not a forecast.
- Normals: 1991–2020 normals for Victoria (Airport) from ECCC’s climate data site, the nearest location with every month of temperature.
- Comparisons: the 2,500-plus towns and neighbourhoods of Canada, each read from its closest normals location; whole cities and reserves aren’t counted.
- Not on this page: a sunshine figure (ECCC published none for 1991–2020) and any lapse-rate correction for height, as the town has no elevation here.
Canadian Climate Normals 1991–2020 · ECCC Data Services End-use Licence. Data Source: Environment and Climate Change Canada
Questions about Duncan’s climate
How warm does Duncan get in summer?
Highs reach 22.7°C on an average July day; no month is warmer.
How cold does Duncan get in winter?
Of all twelve months, February has the coldest nights, about 1.4°C.
How much rain and snow does Duncan get?
Around 901 mm a year in all, from 155 mm in January down to 20 mm in July.
How long does snow stay on the ground?
There is 1 cm of snow or more on the ground on roughly 8 days a year.
Are these figures for Duncan itself?
Not exactly. Duncan lacks a normals station, so Victoria (Airport) supplies the figures.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Duncan →
Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).