You will want a digital night vision scope to use day or night. Old school tube style will burn out during the day.
Thermal can be used day or night. There are advantages and disadvantages.
While thermal works well and anything with body heat sticks out like a sore thumb, anything that is ambient temperature is mostly featureless which makes it a bit of a blank slate looking through the viewfinder.
*When I say thermal can be used during the day, don't look at the sun with it. That will burn it out too.
