You can call moose in all year. They'll come in out of curiosity mostly. They don't come running in like they do during the rut to breed but if they feel like it, they will come in.
If it's hot out, they won't get up for nothing during the day. Your best bet is to be in your spot and start calling and hour before sun up and hopefully get one in and hold him in the area untill legal shooting light.
Also, the rut is governed by hours of daylight...has nothing to do with temperature but some heavy frost sure helps to get them perked up and out running around.