Extreme Heat Wave/Dome Alert
A massive and prolonged heat wave, sometimes called a heat dome, is sitting over large swaths of the U.S. and parts of Canada. There has been a significant rise in temperatures, causing potential danger for industries operating in high heat conditions. This stagnant high-pressure system is trapping heat and humidity, leading to one of the most intense early-summer heat waves on record.
What’s Happening Now
Widespread alerts: As of Thursday, nearly 130 million people were under heat warnings or advisories, according to NOAA’s Weather Prediction Center.
Heat index surges: When combined with oppressive humidity, feels-like temperatures have topped 115°F in several regions.
Historic numbers: NOAA reports that 282 locations broke daily heat records this week, and 121 others tied their all-time highs.
Record-breaking highs: Major cities across the Midwest and East Coast. Some major cities including Chicago, Cleveland, Philadelphia, and New York have experienced highs above 100°F.
Tuesday, June 24th was officially the hottest day in a decade along parts of the East Coast.
Heat Impact in Canada
Southern parts of Ontario, Quebec, and the Prairies have seen unusually high June temperatures, with some areas hitting mid-to-high 30°C (mid-90s°F).
Environment and Climate Change Canada has issued several extended heat warnings this summer, citing humidex values over 40°C (104°F).
Canadian officials are urging outdoor workers to follow heat illness prevention protocols due to increasing reports of heat-related symptoms.
Why Roofing & Construction Workers Are Especially at Risk
Intense surface temperatures: Roofs often exceed air temperatures by 20–30°F, especially dark materials like asphalt and EPDM.
Humidity = Higher risk: Sweat doesn’t evaporate as quickly, impairing the body’s natural cooling system.
Minimal overnight relief: Lows in the 70s–80s°F at night offer limited recovery time for workers doing multiple-day jobs.
Labor intensity: Roofing and exterior construction are among the highest-risk occupations for heat illness according to OSHA.
Essential Safety Measures
Reschedule heavy labor for early morning or late afternoon
Mandatory water breaks every 30–45 minutes with cool, potable water
Lightweight, breathable PPE like moisture-wicking shirts and wide-brim hats
Shaded or cooled rest areas on-site for recovery
Supervisory heat checks and a buddy system to monitor signs of heat stress
Use a Heat Index Chart to plan daily operations and break schedules
Smart Practices = Safe Crews
This isn't just a seasonal hot spell, it's part of a larger climate trend that’s raising baseline temperatures and increasing the severity of extreme weather. Roofing and construction professionals are at the front lines of this reality. As a supply company serving this industry, Big Rock Supply is committed to helping you stay informed, stay prepared, and stay safe.
By proactively adapting schedules, using the right gear, and following the latest guidelines from OSHA and Environment Canada, you can protect your crews and keep projects on track.
For more information on heat related equipment, visit our previous blog on heat safety here.