How to manage the heat without AC?

So we moved in 6 months back when the weather was relatively cooler so we didn't install the AC. December and January was literally so cold at night. Now the past 4 days has been unbearable. So warm and humid at night. We might vacate this house in a couple of months so installing an AC won't be allowed by the landlord. Any other solutions? All our windows are opened (with mosquito net). Apparently coolers won't cool the room and will make the humidity worse. So please give your suggestions please atleast to get through the nights.