Best Temperature to Set Your AC in Burlington During a Heat Wave

Burlington summers have been no joke lately. Whether you’re sweating through a humid July afternoon on New Street or trying to keep a split-level home on the Escarpment comfortable, your air conditioner is working harder than ever — and most people have no idea what’s the best temperature to set your AC to actually use it right.

So what is the best temperature to set your AC when the heat index climbs and your hydro bill is already making you nervous? The answer is more nuanced than “just crank it down.” Let’s break it all down — the right settings, the real costs, what happens when you go too extreme in either direction, and when it’s time to stop Googling and just call a professional.

What Is the Best Temperature to Set Your AC in Summer?

For most Canadian homes — including those in Burlington, Oakville, Hamilton, and the rest of the GTA — the sweet spot is between 23°C and 25°C (73°F to 77°F) during the day when you’re home.

Natural Resources Canada recommends 25°C–26°C as the ideal summer thermostat setting — the Natural Resources Canada energy-saving guidelines support this range for Canadian homes.

Here’s a quick reference:

When you’re home and awake: 23°C – 25°C (73°F – 77°F) When you’re sleeping: 18°C – 22°C (65°F – 72°F) — cooler sleep is actually better for rest When the house is empty: 26°C – 28°C (79°F – 82°F) — no point cooling an empty home

Quick Reference:

• When you’re home and awake: 23°C – 25°C (73°F – 77°F)
• When you’re sleeping: 18°C – 22°C (65°F – 72°F)
• When the house is empty: 26°C – 28°C (79°F – 82°F)

The goal isn’t to make your home feel like a walk-in freezer. It’s to maintain a temperature that’s comfortable enough for humans without abusing your system or your wallet.

Not sure if your central air conditioning system is sized correctly for your home? Oversized or undersized units struggle to hold these temperatures efficiently — check out our guide on how to size your AC properly.

Why This Specific Range? The Science Is Simple

Your body’s internal thermostat works best at ambient temperatures between 20°C and 26°C. Below that range, you’re overcooling — you feel comfortable, but your system is under unnecessary strain. Above 26°C–28°C, the body struggles to regulate, especially in Burlington’s notoriously sticky summer humidity.

Humidity is actually the bigger enemy here, not raw heat. Burlington sits along Lake Ontario, which means humid air masses roll through regularly from June through August. An AC unit doesn’t just cool the air — it removes moisture. That dehumidification is often what makes the temperature feel tolerable, which is why 24°C in Burlington can feel more comfortable than 24°C in a dry climate.

What Happens When You Set Your AC Too Low?

This is where people get themselves into trouble.

Setting your thermostat to 18°C or 19°C because “I want it cold” feels satisfying in the moment. But here’s what’s actually happening behind the scenes:

Your system runs non-stop. Air conditioners are designed to cycle on and off. Continuous operation overheats the compressor and wears out components years before their time.

Ice forms on the evaporator coil. When the AC runs constantly, refrigerant gets too cold and ice builds up — actually reducing cooling efficiency. If you’ve noticed your AC running but not cooling, this is one of the most common culprits.

Your hydro bill spikes hard. Every degree you drop below 24°C increases energy consumption by roughly 3% to 5% per degree. Set your thermostat at 19°C instead of 24°C, and you could be spending 15% to 25% more on cooling — sometimes more during peak summer rates in Ontario.

Uneven cooling. Older Burlington homes — especially those Sidesplit and century homes in the older parts of the city — don’t distribute air evenly at aggressive settings. You’ll freeze one room and ignore the rest.

What Happens When You Set Your AC Too High?

On the flip side, some people try to save money by setting their thermostat at 28°C or 29°C and just “toughing it out.” During a mild day, this might be fine. During a Burlington heat wave with a humidex pushing 40°C, this becomes a health risk, not just a discomfort.

Heat-related stress is real, especially for elderly residents, young children, and anyone with a cardiovascular or respiratory condition. Burlington Public Health typically issues heat alerts several times each summer — those alerts exist for a reason.

Setting your AC too high also means the system has to work harder in short, intense bursts when the indoor temperature finally becomes unbearable — that surge-and-recover cycle isn’t good for the equipment either.

If your home just isn’t cooling down no matter what you set, read our post on AC not cooling in Burlington — the problem may not be your thermostat at all.

The Cost Conversation: What Does Each Degree Actually Cost You?

Let’s put real numbers to this for Burlington homeowners.

Hydro One and Burlington Hydro both use Time-of-Use (TOU) pricing, which means electricity costs more during peak hours — typically weekday afternoons, which is exactly when you want your AC the most.

As a rough benchmark:

• Moving your thermostat from 24°C to 26°C can reduce your cooling costs by 6% to 10% per billing cycle
• Using a programmable or smart thermostat to raise the temperature by 2°C–3°C while you’re at work can save a noticeable amount over a full summer — often $40 to $80 or more depending on your home size
• Each degree of unnecessary cooling adds cost that compounds over the entire season

If you haven’t already, look into the Enbridge or Hydro One rebate programs for smart thermostats — Burlington homeowners are often eligible, and a smart thermostat pays for itself within one or two seasons.

AC Maintenance Tips to Keep Your System Running Strong All Summer

Getting the temperature right is only part of the equation. How long your AC lasts — and how efficiently it performs — comes down to basic maintenance habits most homeowners skip. For a full breakdown, visit our AC maintenance Burlington page — but here are the essentials:

Change or clean your air filter every 4 to 6 weeks during peak summer. A clogged filter is the single most common cause of reduced efficiency and frozen coils. In a dusty or pet-friendly Burlington home, you might need to check it even more frequently.

Keep the outdoor condenser unit clear. That large metal unit sitting outside your home needs at least 60 cm of clearance on all sides. Grass, garden debris, and overgrown shrubs force the unit to work harder and trap heat.

Don’t close vents in unused rooms. It feels logical — if no one’s in that room, close the vent and redirect air. In reality, this disrupts air pressure balance in your ductwork and can cause the system to strain.

Set your ceiling fans to run counterclockwise in summer. This pushes cool air downward and can let you comfortably raise your thermostat by 2°C without noticing the difference — free savings.

Schedule annual preventative maintenance before summer hits. A quick refrigerant check, coil cleaning, and electrical inspection in April or May can catch small problems before they become $2,000 compressor replacements in mid-July. Our AC maintenance team in Burlington can handle this in one visit.

Keep blinds and curtains closed on south and west-facing windows during peak afternoon heat. On a hot day, sunlight through windows generates significant heat gain — your AC fights that battle every minute the blinds are open.

When Do You Actually Need to Call an HVAC Contractor?

There’s a big difference between “my house feels a little warm” and “something is genuinely wrong with my system.” Here are the signs that mean it’s time to pick up the phone and call a licensed HVAC contractor in Burlington: see AC repair warning signs

Warm air blowing from vents even when the thermostat is set to cool — this typically points to a refrigerant issue or a failing compressor. See our AC repair Burlington

Unusual sounds — grinding, banging, squealing, or persistent clicking when the system cycles — are not normal and usually indicate a mechanical problem that will get worse if ignored.

Water pooling around the indoor air handler. A small amount of condensation is normal. A puddle or a dripping unit is not — it usually signals a blocked condensate drain or a frozen evaporator coil thawing and overflowing.

Skyrocketing hydro bills without a change in habits. If your bill jumps significantly compared to the same month last year and nothing in your household has changed, your AC is likely losing efficiency due to a mechanical issue. Check our AC repair cost guide to understand what to expect.

The system short-cycles — turns on, runs for a minute or two, shuts off, and repeats constantly. This wastes energy and strains the compressor.

Your system is over 12 to 15 years old and struggling. At that age, Burlington HVAC contractors will often recommend evaluating repair-versus-replace options, especially if your unit uses R-22 refrigerant, which has been phased out in Canada. Explore your options on our AC replacement Burlington

Don’t wait until a sweltering August afternoon to call — that’s when every HVAC technician in Burlington and Hamilton is already booked solid for two weeks.

For urgent issues, our emergency AC repair Burlington team is available when you need same-day help.

One Last Thing Worth Knowing

If you remember nothing else from this post, remember this: the best temperature to set your AC is the highest setting where you’re still genuinely comfortable. Not the lowest. Not “as cold as possible.”

That mindset shift — from “blast it” to “right-size it” — saves money, extends the life of your equipment, and puts less strain on the grid during Burlington’s peak demand hours, when the whole city is trying to stay cool at the same time.

A smart thermostat, a clean filter, and one annual maintenance visit from a local HVAC professional will do more for your summer comfort than any aggressive thermostat setting ever will.

Also wondering whether a heat pump might be a better long-term solution for your Burlington home than a traditional central AC? It’s worth reading before your next replacement decision.

Stay cool out there, Burlington.

Frequently Asked Questions