When it gets really cold I keep the feeders inside at night. The sun was not up at 7:25am this morning (2-6-19), but the hummer was at the feeder as soon as I hung it up. It did not even wait for me to back off before it perched on the feeder to feed. It is about 12*F according to the thermometer on the back deck, so the fluid will freeze in about an hour. I will have to swap feeders until the sun is shining on the feeder and keeps the fluid from freezing.