When should I turn on my AC in Ottawa?

In Ottawa, you can typically start using your air conditioning when daytime temperatures consistently reach 20-22°C (68-72°F) and nighttime temperatures stay above 15°C (59°F). This usually happens in late May or early June, though Ottawa's unpredictable spring weather means some years you might need it as early as mid-May or not until mid-June.

The key is watching for sustained warm weather rather than just a single hot day. Ottawa's spring can swing from 25°C one day to 10°C the next, so resist the urge to fire up the AC for just one or two warm days. Your system works most efficiently when outdoor temperatures are consistently warm, and you'll save money by waiting for truly sustained heat.

Before turning on your AC for the season, take a few important steps. Check that your outdoor unit is clear of debris, leaves, and winter buildup. Replace your furnace filter if it's been more than 3 months, as a dirty filter will make your AC work harder and less efficiently. Make sure all vents inside your home are open and unobstructed.

In Ottawa's climate, many homeowners find that setting the thermostat to 24-25°C (75-77°F) during the day and 22°C (72°F) at night provides good comfort while keeping hydro bills reasonable. Remember that your AC removes humidity as well as heat, so you might feel comfortable at slightly higher temperatures than you'd expect.

If your AC hasn't been serviced in the past year, consider scheduling a tune-up before the peak summer season. This ensures optimal performance during Ottawa's hot, humid summer days and can prevent breakdowns when you need cooling most.