Heat rules in Washington: the Outdoor Heat Exposure rules

This page reports what the official source says. It is not legal advice: ask the office named here. It restates the Washington State Department of Labor and Industries (L&I) outdoor heat exposure page and its questions and answers on the rule, as read on October 8, 2026. The page says the Outdoor Heat Exposure rules were adopted June 27, 2023 and took effect July 17, 2023. The comparison of every place is on the heat rules overview.

Action levels and scope

The L&I questions and answers say the outdoor temperature action level was lowered for most situations from 89 degrees Fahrenheit to 80 degrees, and that the level is 52 degrees for workers wearing non-breathable clothing. The previous rules ran from May 1 through September 30. L&I says the 52 degree level can occur at other times of the year and that, while not common, the 80 degree level can occur outside May through September, so the adopted rules apply year-round. The rules cover work in an outdoor environment, and L&I says work inside vehicle cabs, sheds and tents may count as outdoor if the temperature is not managed by engineering controls. Indoor ambient heat is described as a second phase of rulemaking, once initiated.

What the rules require

L&I lists the current requirements for outdoor heat exposure:

• address outdoor heat exposure in the required Accident Prevention Program;
• annual training for employees and supervisors on symptoms and the employer's policies;
• enough cool drinking water, with opportunities to drink it;
• adequate shade or alternative cooling methods at all times;
• paid rest breaks when a worker feels the need to cool down;
• close observation of workers not acclimatized, including new employees, those returning from absences, and all workers during a heat wave;
• emergency procedures for any worker with symptoms, and a way for supervisors and employees to communicate.

At 90 degrees and above, L&I says additional paid cool-down rest periods of at least 10 minutes every 2 hours are required. Its answers add that at 100 degrees and above the mandatory rest is 15 minutes per hour, and that the 100 degree rest applies only for the times the temperature reaches that level, not the whole day. Mandatory periods are in addition to preventative cool-down rests, which are available any time the temperature is at or above the action level. The answers say the high-heat requirements apply unless engineering or administrative controls, such as air conditioning or scheduling work at cooler times, bring exposure below 90 degrees, and that wearable items such as cooling vests and towels do not count as engineering controls.

Other details in the answers

For acclimatization, the answers say the 14 day period for new and returning workers does not start over if the temperature drops below 80 degrees. On water, they say the adopted rule avoids requiring employers to measure water temperature, and cite NIOSH and OSHA guidance of 50 to 60 degrees Fahrenheit as recommended for drinking water. L&I says the 2008 action levels were derived using wet bulb globe temperature, OSHA's heat standards page lists Washington among the states with their own heat rule, and OSHA's Federal Register notice describes the Washington standard as covering outdoor workplaces only.

Sources

• Washington State Department of Labor and Industries, Outdoor heat exposure rules and resources, read October 8, 2026
• OSHA, Heat standards in specific states, read October 8, 2026
• Federal Register, Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings, proposed rule of August 30, 2024, read October 8, 2026