Composting worms like the same temperatures that we do. There ideal range is 60-80 degrees Fahrenheit. Go to your worm composting bin. If you are cold, so are they. If you are hot, so are your worms. While your composting worms will tolerate temperatures outside this ideal range, do your best to keep the temp within 60-80 degrees F because this is when your worms are most productive.
To learn more about regulating the temperature of your worm composting bin read: Regulating Temperature in your Worm Bin