Workplace Temperature Regulations in Ontario: Too Hot or Too Cold to Work?

Ontario does not have one minimum and maximum temperature that applies to every workplace. Enclosed workplaces covered by the Industrial Establishments regulation generally must be at least 18°C, subject to exceptions. There is no universal maximum workplace temperature or outdoor temperature that automatically stops all work. However, employers must protect workers from dangerous heat and cold.

Whether you work in an office, warehouse, restaurant or outdoors, the conditions where you actually work matter. A broken heater, extreme humidity or hours outside without adequate protection can create a workplace safety concern.

If your employer threatens, disciplines or fires you for raising a safety concern, the Ontario employment lawyers at Samfiru Tumarkin LLP can review your situation and explain your options.

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On This Page:

• 1. Temperature Rules
• 2. Too Hot to Work
• 3. Too Cold to Work
• 4. Refusing Unsafe Work
• 5. Threats, Discipline & Dismissal
• 6. Frequently Asked Questions
• 7. Get Legal Help

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The rules depend on the workplace and the type of work being performed. A heated office, refrigerated storage facility and outdoor construction site do not all have the same temperature requirements.

Under the Occupational Health and Safety Act (OHSA), employers must take reasonable precautions to protect workers. That obligation applies even where there is no specific temperature limit.

This guide covers provincially regulated Ontario workplaces. Sector-specific requirements may also apply, and federally regulated workplaces follow different rules.

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Hot weather does not automatically cancel work, but your employer cannot ignore dangerous heat. If the conditions give you reason to believe your work is likely to endanger you, you may have grounds to start the unsafe-work refusal process.

Heat can be a problem indoors as well as outdoors. Kitchens, factories, warehouses and workplaces with heat-producing equipment can become hazardous even when the outdoor forecast does not look extreme.

What temperature is too hot to work in Ontario?

There is no general rule that every Ontario workplace must shut down at 30°C or 35°C. A thermometer reading alone does not show the full risk.

A heat assessment should consider:

• Humidity and airflow: Humid, poorly ventilated conditions can make it harder to cool down.
• Sunlight and other heat sources: Direct sun, ovens, machinery and hot surfaces can increase exposure.
• Physical effort and clothing: Heavy work and protective equipment can increase the heat your body must manage.
• Time exposed and recovery: Long periods without adequate cooling breaks can increase the risk.

Conditions should be assessed where the work happens, not just at a nearby weather station. An official heat warning is useful information, but it is not the only reason to take precautions.

Are heat breaks required in Ontario?

Additional cooling breaks may be necessary to protect workers from heat stress. Ontario does not prescribe one heat-break schedule that applies to every worker at a particular air temperature.

The frequency and length of breaks should reflect the conditions, workload and opportunity to recover in a cooler area. Heavy work, protective clothing and increasing heat can require more frequent rest.

These safety precautions are separate from ordinary meal and break-time rules in Ontario. Providing a regular lunch break does not remove an employer’s obligation to address dangerous heat.

What should your employer do to reduce heat stress?

Depending on the workplace, reasonable precautions can include:

• Reducing heat at its source and improving ventilation or cooling.
• Providing access to cool drinking water and cooler or shaded rest areas.
• Adjusting the workload, pace or schedule, including moving strenuous tasks to cooler periods.
• Providing suitable breaks, training and a plan for responding to heat-related illness.

Ontario’s heat-stress guidance explains these precautions. The right combination depends on the actual hazard; simply telling employees to “drink more water” may not adequately address the conditions.

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Employers must address dangerous cold, whether you work inside an unheated building or outdoors. Cold weather does not automatically stop all work, but the absence of a universal outdoor cutoff does not make every cold-weather assignment safe.

What is the minimum workplace temperature in Ontario?

Section 129 of Ontario’s Industrial Establishments regulation generally requires an enclosed workplace covered by that regulation to be at least 18°C and suitable for the type of work performed.

The 18°C minimum has exceptions. These include workplaces that are normally unheated, areas where necessary door opening makes that temperature impractical, and spaces used to process or store perishable goods requiring colder conditions.

An exception to the minimum does not remove the employer’s broader obligation to protect workers from cold-related hazards. Other sectors can also have their own temperature requirements.

What if there is no heat in your workplace?

Report a heating failure or unusually cold indoor conditions promptly. Note the temperature, location, how long the problem has lasted and how it affects your ability to work safely.

Ask what temporary measures will be taken while the problem is addressed. Depending on the circumstances, these could include a suitable alternative work area, safe temporary heating or changes to duties.

Do not assume that feeling cold automatically allows you to leave work. Equally, your employer should not dismiss a possible safety or minimum-temperature violation as a personal preference.

When is it too cold to work outside in Ontario?

Ontario does not have one outdoor temperature at which every worker must stop. Wind chill, wet clothing, exposure time, physical activity and access to shelter all affect the risk.

For example, a brief outdoor task with suitable protection presents a different situation from several hours in wind and wet conditions without a place to warm up.

An extreme cold warning does not automatically establish a right to refuse every outdoor task. It should prompt a serious review of the conditions and precautions. Cold can also be hazardous when no warning has been issued.

Should outdoor workers receive warming breaks?

Warming breaks and access to a warm, dry shelter can be important protections against cold stress. Other precautions can include suitable clothing and equipment, limiting exposure, monitoring workers and rescheduling tasks.

The Canadian Centre for Occupational Health and Safety’s cold-work guidance explains how work and warming schedules can account for the conditions. A recommended schedule should not be mistaken for one universal Ontario law.

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You may refuse work if you have reason to believe the physical conditions are likely to endanger you, subject to the OHSA’s rules and exceptions. You do not have to wait until you are injured to raise a safety concern.

The work-refusal process generally involves:

1. Reporting the refusal immediately. Tell your supervisor or employer which work you are refusing and why you believe it is dangerous.
2. An immediate investigation. Your employer investigates with you and the appropriate worker representative.
3. Remaining safely available. Stay in a safe place as near as reasonably possible to your workstation for the investigation. Do not simply leave without following the process.
4. Contacting the Ministry if unresolved. If you still have reasonable grounds to believe the work is dangerous, the Ministry must be notified so an inspector can investigate. Reasonable alternative work may be assigned while that investigation is pending.

Some healthcare and emergency-service workers have limits on their right to refuse. For the full process and exceptions, read our guide to refusing unsafe work in Ontario.

Keep relevant records, including your written concerns, temperature readings, the employer’s response and any instructions you received. Record where and when readings were taken; conditions can differ across a workplace.

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Your employer can’t lawfully punish you for exercising your rights under the OHSA. This includes asking the employer to address unsafe conditions or exercising the right to refuse unsafe work.

Prohibited retaliation can include threats of dismissal, discipline, suspension, intimidation or cutting your hours because you raised a protected safety concern.

An employer does not make an unlawful safety-related dismissal legal simply by offering severance. A complaint to the Ontario Labour Relations Board may lead to remedies such as compensation, reinstatement or removal of a penalty.

If you have been threatened, disciplined or dismissed, get advice about your options before signing a release. An employment lawyer can assess possible safety-reprisal remedies and any wrongful dismissal compensation.

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Does my employer have to provide air conditioning?

There is no blanket requirement that every Ontario workplace have air conditioning. However, your employer must meet applicable safety requirements and adequately address heat hazards. Depending on the conditions, effective measures could include cooling, ventilation, changes to work or access to cooler rest areas.

A lack of air conditioning does not automatically make a workplace illegal. It also does not excuse dangerous heat.

Are heat breaks and warming breaks paid?

Under Ontario’s employment standards guidance, employees covered by the applicable rules who must remain at the workplace during breaks other than eating periods must be paid at least minimum wage for that time. An employment contract or workplace policy may provide a greater entitlement.

The answer therefore depends on the type of break and the circumstances. A required cooling or warming break should not automatically be treated as an unpaid meal break.

What if a medical condition makes heat or cold unsafe for me?

Tell your employer about your work-related limitations and request accommodation. Your healthcare provider can help explain the restrictions or adjustments you need.

Where the need is disability-related, the employer must consider accommodation up to the point of undue hardship. Possible adjustments might include a different work area, modified duties or changes to the schedule. A temperature that others tolerate may still create an accommodation need for you.

Can I quit because of unsafe temperatures and receive severance?

Serious, unresolved unsafe conditions may raise a constructive dismissal issue, but an uncomfortable workplace does not automatically give you a right to resign and collect severance.

Get advice before resigning or signing an exit agreement. If you are in immediate danger, prioritize safety and use the appropriate reporting and work-refusal process.

What if the problem is travelling to work in extreme weather?

Dangerous working conditions and difficulty commuting are different issues. A snowstorm, road closure or weather warning does not automatically give every employee the right to stay home with pay.

For attendance, closures and weather-related absences, read our guide to employee rights during inclement weather in Ontario.

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You should not have to choose between raising a legitimate safety concern and protecting your job.

Samfiru Tumarkin LLP helps non-unionized employees in Ontario understand their rights after workplace threats, discipline, dismissal or pressure to resign. We can review the employer’s response, explain the available options and help you pursue compensation or other remedies where appropriate.

The Ministry of Labour addresses workplace hazards and investigates work refusals. Our employment lawyers can advise you about the employment consequences and your legal options.

Unionized? Workplace safety rights can still apply. Contact your union about representation and grievance options. Our firm can’t help with unionized employment law matters.

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