Add ice to portable air conditioners’ tank. Alternatively, there's the Alivio 4L Portable Air Cooler Humidifier 65W with 3 Fan Speeds. I have been using this portable fan for a few days now, and it works really well for personal cooling. I like how compact and lightweight it is, a good value for the price and a practical little cooling fan for hot days." I can now actually sleep at night.