CHICAGO (WLS) — Although overall opioid overdose incidents have been decreasing citywide over the last few years, a sudden increase occurred over the weekend, resulting in the year’s first red alert.

Health officials told ABC7 the hot temperatures may be to blame, at least, in part.

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This past Saturday, as temperatures climbed, so did the emergency calls for opioid overdoses, surpassing 37 cases — a threshold set by the Chicago Department of Public Health to issue a red alert.

“We often observe that as the weather gets warmer, the average number of overdoses tends to rise,” explained Miao Jenny Hua, Deputy Commissioner of the Chicago Department of Public Health.

Health officials say the spike is similar to the one that also occurs in gun violence and domestic violence incidents during the summer months and can be partly attributed to the specific nature of where these overdoses occur.

“Five neighborhoods on the West Side of Chicago account for something like a third of all overdoses that happen citywide. Over half of those overdoses do occur outside,” Hua said.

A former heroin addict himself, Marnell Brown runs an organization called To Walk in My Shoes. He and his team drive around those five neighborhoods, East Garfield Park, West Garfield Park, North Lawndale, Austin and Humboldt Park, administering Narcan to those in distress.

“Once they get their drug, they don’t go on the inside and do their drugs. They do their drugs right there on the spot or leaving the spot,” Brown said.

This weekend, he says, was busy.

“We seen more activity Saturday than we’ve seen in the past Saturdays,” Brown said. “People just have a different reaction to fentanyl when they’re in the heat.”

But while Chicago EMS dispatch records do show a definite increase in the number of overdose calls during the summer months, health officials say not all red alert spikes are triggered by heat. The introduction of new substances into the drug supply can also lead to a spike and so can holidays. Last year’s only red alert came on Mother’s Day when the high was only 66 degrees.

Ultimately, beating addition is the only way to continue to bring those numbers down. Free and immediate medication assisted treatments are available to all Illinois residents at 833-234-6343, or text “HELP” to 833234.

Click here for more information about the hotline.