Also, just a word of unsolicited advice, chicken wire is not protective against most predators. It's only designed to keep chickens in or out. Half-inch hardware cloth is stouter and will protect against most predators when properly installed. Good luck and enjoy your flock!
How cold will it be by morning? How many are there? In your pic they look like day-old to week-old chicks (on my phone).
General rule of thumb, as far as I know, is that chicks in their first week should have access to heat up to 85-90°F with slightly cooler temps also accessible. Lower the...