we re seeing 180 to 150 lightning strikes in the last 15 minutes. when you hear thunder, move indoors. don t stay outside if you can help it. things calm down after midnight, but more tomorrow of the same. on days like today, people who work in an air-conditioned office are much happier than the folks working outside. many new yorkers, particularly people in public housing, don t news 4 investigates just found out how hot the unair-conditioned apartment can get in weather like this. reporter: natalie, air-conditioning a savior on days like today. for those who can t afford it, it is just a luxury. here in harlem five stories up no ac. harlem apartment, victor sanchez says it gets unbearable. i wouldn t be surprised if it hit 97, 98 degrees. reporter: he can only dream of cooling off inside. air-conditioning is expensive to buy and expensive to run. reporter: he is among 10% of new yorkers that don t have air-conditioning. now he is part of a ground breaking study