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Heat rules for outdoor work, place by place

A side by side of the outdoor heat rules that official sources describe for the United States and the states that have their own, with the temperature triggers, water, shade and rest requirements as each rule words them.

Checked against the sources at the bottom of this page on October 8, 2026. Rules, fees and pay change: the source has the last word.

This page reports what the official source says. It is not legal advice: ask the office named here. It sets out the heat rules that OSHA and the state agencies describe on their own pages, as read on October 8, 2026. It describes rules; it does not tell any crew what to do. Tree crews work outdoors in heat, in harnesses and chainsaw clothing, and the sources below use different measures: some use air temperature, some use the heat index, and Washington uses a lower trigger for non-breathable clothing. The units are kept as each source writes them. For the health effects of the work see the guide to health hazards of tree work.

United States, and the states with their own rule

There is no final federal heat standard. OSHA's rulemaking page lists a proposed rule published August 30, 2024, and a hearing that ended on July 2, 2025. Until a rule exists, OSHA's page on heat standards points to the General Duty Clause. OSHA's page lists five states with their own heat standard: California, Colorado, Minnesota, Oregon and Washington.

PlaceTrigger as the source writes itMain requirements named
United States (federal)Proposed rule: heat index of 80 degrees Fahrenheit (initial) and 90 degrees Fahrenheit (high heat). No final ruleProposal: a plan to evaluate and control heat hazards. Until a final rule: General Duty Clause. See the United States page
CaliforniaOutdoor temperature above 80 degrees Fahrenheit for shade; 95 degrees Fahrenheit for high-heat procedures. Indoor rule at 82 degrees FahrenheitWater, shade, cool-down rest, high-heat procedures, acclimatization, training, written plan. Landscaping and construction are listed industries. See the California page
WashingtonTemperature action level 80 degrees Fahrenheit, or 52 degrees Fahrenheit for non-breathable clothing; 90 and 100 degrees Fahrenheit for mandatory restWater, shade, paid rest, observation of unacclimatized workers, training. See the Washington page
OregonHeat index of 80 degrees Fahrenheit; high-heat practices when controls do not bring it below 90 degrees FahrenheitShade, water up to 32 ounces per hour, rest break schedule, plan, annual training. See the Oregon page
ColoradoOSHA's page points only to the Agricultural Labor Conditions RulesAgricultural sites only, per OSHA's page
MinnesotaOSHA's page says the standard applies to indoor places of employmentIndoor only, per OSHA's page
MarylandHeat index of 80 degrees Fahrenheit, indoors or outdoors; high-heat procedures at 90 degrees FahrenheitWritten plan, acclimatization, shade, 32 ounces of water an hour, rest periods at 90 and 100, training. In effect since September 30, 2024. See the Maryland page
CanadaBritish Columbia: ACGIH screening criteria as an exposure limit. Ontario: no numeric limit, general dutyBC: assessment, exposure control plan, controls, water, removal from heat. See the Canada page
United KingdomNo legal maximum working temperature, as HSE words itGeneral health and safety duties; HSE's outdoor working list. See the United Kingdom page
AustraliaNo stop-work temperature in New South Wales or Victoria, as each regulator words itDuty to manage the risk so far as reasonably practicable. See the Australia page
New ZealandNo minimum or maximum safe temperature in the Health and Safety at Work Act 2015, as WorkSafe words itDuty to manage so far as reasonably practicable. See the New Zealand page

How the triggers compare

The triggers differ in what they measure. California and Washington measure air temperature, and the Federal Register notice says both cover outdoor workplaces only. Oregon uses the heat index, which combines temperature and humidity, and covers indoor and outdoor work. In its proposal OSHA says it chose a heat index of 80 degrees Fahrenheit as the same initial trigger as Oregon's rule and Maryland's proposal, and notes that California and Colorado use an ambient temperature of 80 degrees Fahrenheit. The California, Washington and Oregon rules all set shade at the 80 degree level and add stricter procedures near 90 or 95 degrees.

Heat rules, place by place

Sources