Summer nights are getting hotter. Here's why that’s a health and wildfire risk
By Georgina Gustin
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Cooler nighttime temperatures allow bodies to "reset" and recover from scorching daytime highs as buildings and houses cool. But when external temperatures stay above 80 degrees, internal body temperatures don't have a chance to cool.
If humidity is also high—as was the case in Quebec this week—the body perspires more, but the humidity means sweat can't evaporate, cranking up internal temperatures even more. Recent research has shown that higher nighttime temperatures can also mean less sleep, potentially adding more physical stress on the body.
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Warmer nighttime temperatures also mean earlier frost-free dates and later first-frost dates, so pests aren't killed by cold temperatures and weeds have more time to grow. Warmer nighttime temperatures also increase transpiration from some crops, drying them out, introducing health problems and lowering yield. In certain areas, this can also lead to increased risk of fire.
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Firefighters historically have counted on lower temperatures and higher humidity at night to bring "recovery" periods that help them tamp down blazes, but that's been changing. Hot air holds more moisture, meaning lower relative humidity, so fires can continue to rage through the night.
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