When to change furnace filters
Check your furnace filter monthly. Clean a reusable filter or replace a disposable one when its instructions and your system call for it. These reminders use local climate normals only to highlight heating-season months.
Monthly check reminders, not automatic replacement dates.
Why a scheduled filter matters
ENERGY STAR recommends checking the filter once a month. Clean it if it is reusable or replace it if it is disposable and needs changing, following the instructions for your system and filter.
The dates above use the 30-year mean monthly temperature at your nearest station to mark a local heating-season window. They are monthly prompts to check the filter, not a forecast or a direction to replace it every month.
Heating season and monthly filter checks for major cities
| City | Heating season | Monthly filter checks | |
|---|---|---|---|
| Victoria | BC | October to April | 7 |
| Vancouver | BC | November to April | 6 |
| Kelowna | BC | October to April | 7 |
| Calgary | AB | October to May | 8 |
| Edmonton | AB | October to April | 7 |
| Saskatoon Diefenbaker | SK | October to April | 7 |
| Regina | SK | October to April | 7 |
| Winnipeg Richardson | MB | October to April | 7 |
| Sudbury | ON | October to April | 7 |
| Ottawa Cda | ON | October to April | 7 |
| Toronto Lester B. Pearson | ON | October to April | 7 |
| Windsor | ON | November to April | 6 |
| Montreal/Pierre Elliott Trudeau | QC | October to April | 7 |
| Quebec/Jean Lesage | QC | October to April | 7 |
| Fredericton | NB | October to April | 7 |
| Halifax Stanfield | NS | October to May | 8 |
| Charlottetown | PE | October to May | 8 |
| Whitehorse | YT | September to May | 9 |
| Yellowknife | NT | September to May | 9 |
Related tools
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Questions, answered plainly
How often should I check my furnace filter?
Check it once a month. Clean a reusable filter or replace a disposable one only as its instructions and your system manual say; a dirty filter may need attention sooner.
Which replacement filter should I buy?
Use the size and type specified by your equipment or filter instructions. If you are unsure which rating your system supports, ask the manufacturer or an HVAC professional before choosing a different filter.
Why does the schedule vary by place?
Heating season is longer in Winnipeg than in Vancouver. The dates above are monthly check reminders across the months whose station mean temperature is at or below 10 C; they are not a replacement schedule.
How this page was made
Data source: Environment and Climate Change Canada 30-year climate normals via the site dataset. Method: heating season is the contiguous run of months with mean temperature at or below 10 C; the calendar places a monthly filter-check reminder in each month of that run. ENERGY STAR says to inspect, clean, or change air filters once a month; the right maintenance action depends on whether the filter is reusable and on its instructions. Content reviewed 2026-09-27. ENERGY STAR maintenance checklist. Full notes on the methodology page.