Workplace Temperature Regulations in Ontario: Can You Refuse to Work if It’s Too Hot?

TL;DR – Working in Extreme Heat in Ontario

What Temperature Is Too Hot to Work in Ontario?

Ontario law doesn’t define an exact temperature that’s “too hot” to work. However, under the Occupational Health and Safety Act (OHSA), employers must take every reasonable precaution to keep the workplace safe.

The Ministry of Labour considers heat stress a workplace hazard. As a general rule, heat becomes dangerous when the temperature climbs above 26–30°C, especially when combined with humidity, physical exertion, or personal protective equipment (PPE).

What Measures Can Employers Take to Prevent Heat Stress?

While not legally required to follow a specific temperature threshold, employers are expected to implement heat stress prevention measures, including:

• More frequent and longer rest breaks
• Scheduling heavy tasks during cooler times of day
• Providing shaded or air-conditioned rest areas
• Supplying cold drinking water at all times
• Encouraging hydration throughout the day
• Avoiding work in direct sunlight when possible
• Training employees to recognize signs of heat exhaustion and stroke
• Having an emergency plan in case of heat-related illness

Can I Refuse to Work If It’s Too Hot?

Yes. Under the OHSA, you have the legal right to refuse unsafe work—including work that puts your health at risk due to extreme heat.

Here’s How To Do It Properly:

1. Tell Your Supervisor
   Let them know that you believe the temperature or working conditions are unsafe. Be clear and specific (e.g., “There’s no shade or water on-site, and it’s 35°C”).
2. Involve the Ministry of Labour
   If your employer doesn’t take appropriate steps to address the issue, contact the Ministry of Labour. They will investigate and can issue orders if necessary.

What If My Employer Ignores Heat Safety?

If your employer isn’t following heat stress guidelines or has no clear plan to keep workers safe in extreme heat, take these steps:

1. Document the conditions – note the temperature, time of day, lack of water or rest areas, etc.
2. Raise the issue internally – ask them to follow the Ministry of Labour’s heat stress prevention guidelines.
3. File a complaint – contact the Ministry of Labour and file a complaint if they refuse to act.

FAQ: Heat Stress and Workplace Rights in Ontario

Is There a Legal Maximum Temperature for Working in Ontario?

No. But employers must still ensure safe working conditions under the OHSA.

Can My Boss Punish Me for Refusing to Work in the Heat?

No. As long as you follow the legal process, you are protected.

Does Ontario Have Official Guidelines for Working in Hot Conditions?

Yes. The Ministry of Labour provides detailed guidance, even though it isn’t law.

What if I Work in Construction or Outdoors?

You’re at higher risk and should receive more frequent breaks, shaded areas, and access to water. Read more about severance pay for construction workers.

Get Legal Help if You’ve Been Penalized for Refusing Unsafe Work

If you’re a non-unionized employee in Ontario and you’ve been punished, disciplined, or fired after refusing to work in extreme heat, you may be owed severance pay and additional compensation.

At Samfiru Tumarkin LLP, our team—operating through our Ottawa and Toronto employment lawyer offices, has helped thousands of non-unionized individuals enforce their employment rights when their employer failed to follow the law.

• 👥 Over 50,000 clients helped across Canada
• 💰 Millions recovered in severance and compensation
• ⚖️ No win, no fee — you don’t pay unless we win*
• ⭐ 2,277 5-star Google reviews across Ontario (4.8 average)
• 🏆 Recognized as one of Canada’s Best Law Firms by The Globe and Mail

*Conditions apply. Not all cases qualify.

Contact us online or call 1-855-821-5900 to speak with an experienced Ontario employment lawyer today.