With temperatures set to drop below 30 degrees overnight, New York City has issued the first Code Blue of the fall season.

The emergency weather warning, issued by the city’s Department of Homeless Services, goes into effect Tuesday at 4 p.m. and will remain in effect until 8 a.m. Wednesday, New York City Emergency Management said.

The Department of Homeless Services issues Code Blue notices when temperatures drop to 32 degrees or lower between 4 p.m. and 8 a.m., taking wind chill into account.

Temperatures will hold steady around 50 degrees during the day Tuesday before the coolest air of the season moves in during the evening hours. Lows are expected to dip into the 30s on Wednesday morning.

NY1 meteorologist Guy Brown said wind chill will drop into the upper 20s Wednesday morning due to strong and persistent wind gusts.

“Outreach teams will survey all five boroughs to connect our most vulnerable New Yorkers with shelters,” New York City Emergency Management said. “No one who is homeless and seeking shelter in New York City during a Code Blue will be turned away.”

The city is asking New Yorkers to call 311 if they see someone who is homeless and needs help.

The forecast for Thursday looks the same, although no Code Blue has yet been issued for that day.