Winter vs Summer Electricity Costs in Ontario
Updated 2026‑04‑22
Electricity costs in Ontario change dramatically between winter and summer, even when your habits stay the same. Heating and cooling loads, daylight hours, seasonal pricing thresholds, and weather patterns all influence how much electricity a home uses. This guide explains the real reasons bills rise in different seasons, using plain English and practical examples so households can understand what they are paying for.
1. Heating vs cooling — the biggest seasonal difference
For most Ontario households, the largest seasonal driver of electricity use is the difference between winter heating and summer cooling.
Winter: heating loads can dominate electricity use
Homes that heat with electricity—baseboards, heat pumps, or electric furnaces—can see winter usage double or triple compared to fall or spring. Even gas‑heated homes often use more electricity in winter because:
- furnace blowers run more often
- space heaters are used in basements or bedrooms
- lights stay on longer due to shorter days
- humidifiers run continuously
Summer: air conditioning is a major load
Central air conditioning, window units, and heat pumps can add 200–600 kWh per month depending on home size and outdoor temperatures. A single heat wave can noticeably increase a bill.
In short: winter heating and summer cooling are the two biggest seasonal drivers of electricity costs in Ontario.
2. Seasonal Tier 1 thresholds (Tiered pricing)
If you use Tiered pricing, the Tier 1 limit changes seasonally:
- Winter: 1,000 kWh/month
- Summer: 600 kWh/month
This means you can use more electricity at the lower Tier 1 rate in winter. In summer, the lower threshold means more usage may fall into Tier 2, even if your habits don’t change.
For households with air conditioning, this can make summer bills feel higher even when usage is similar to winter.
3. Time‑of‑Use (TOU) patterns shift with the seasons
Under TOU pricing, the cost of electricity depends on when you use it. Seasonal routines often change your usage pattern without you realizing it.
Winter TOU patterns
- More lighting during dark mornings and evenings
- More cooking and indoor activity during peak hours
- Electric heating running during morning and evening peaks
Summer TOU patterns
- Air conditioning running during afternoon on‑peak periods
- More laundry and dishwashing during weekends or evenings
- Fans and dehumidifiers running continuously
Even small shifts in when you use electricity can change the energy portion of your bill.
4. Weather extremes increase system‑wide demand
Ontario’s electricity system experiences its highest demand during:
- very cold winter mornings
- very hot summer afternoons
High demand affects wholesale electricity prices and system costs. While most households pay regulated prices, these underlying system costs influence the Global Adjustment and other components built into TOU, Tiered, and ULO rates.
5. Longer or shorter billing periods
Billing periods are not always exactly one month. Utilities often bill in cycles ranging from 27 to 33 days. A longer billing period can make a bill look higher even if daily usage stayed the same.
Always check the “Number of Days” on your bill before comparing winter and summer totals.
6. Humidity control and ventilation
Humidity plays a major role in electricity use:
Summer
- dehumidifiers can use 30–60 kWh per week
- air conditioners work harder when humidity is high
Winter
- humidifiers run frequently to maintain comfort
- HRVs/ERVs increase ventilation loads
These devices often run quietly in the background, making their impact easy to overlook.
7. Seasonal lifestyle changes
Electricity use often changes with the season due to lifestyle patterns:
Winter
- more time spent indoors
- more cooking and baking
- more laundry (heavier clothing, bedding)
- holiday gatherings and lighting
Summer
- more laundry from outdoor activities
- pool pumps and heaters
- EV charging after road trips
- more showers and hot water use
Even if you don’t consciously change your habits, seasonal routines often increase electricity use.
8. Appliance performance changes with temperature
Some appliances use more electricity depending on the season:
- Refrigerators work harder in hot weather
- Water heaters use more energy in winter because incoming water is colder
- Heat pumps use more energy in extreme cold or heat
- Dryers run longer in humid weather
These changes are normal and often explain small seasonal differences in usage.
9. Delivery charges can vary with usage
Delivery charges include fixed and variable components. The variable portion is tied to how much electricity you use. Since usage changes seasonally, delivery charges often rise in winter and summer compared to spring and fall.
Delivery charges also change when utilities update their rates through Ontario Energy Board applications.
10. Global Adjustment (GA) and system costs
The Global Adjustment covers the cost of electricity generation contracts, conservation programs, and system reliability. GA can vary month to month based on:
- market electricity prices
- contracted generation costs
- system demand
Because GA is built into TOU, Tiered, and ULO prices, seasonal system conditions can influence the energy portion of your bill.
11. Comparing winter and summer bills correctly
To compare bills accurately, check:
- Billing period length — 27 vs 33 days makes a big difference.
- Total kWh used — compare to the same month last year.
- Rate plan — TOU, Tiered, or ULO.
- Seasonal Tier 1 threshold — 600 vs 1,000 kWh.
- Weather differences — colder or hotter months use more energy.
- Household changes — guests, work‑from‑home, new appliances.
Most seasonal differences can be explained by one or two of these factors.
12. Which season is usually more expensive?
For most Ontario households:
- Electric‑heated homes: winter is usually more expensive
- Gas‑heated homes with central AC: summer can be similar or slightly lower
- Homes with heat pumps: winter and summer can be comparable depending on temperature
However, the exact answer depends on your home, appliances, insulation, and habits.