Thermal imagers or temperature indicators are nice but only give you a "snapshot" of what is going at that very instant. There are available some small stick on tabs that have a permanent change in color at a specific temperature. some are marketed for electrical use. You put the sticker on the termination and then every few months you just look for the color change and take any corrective action that may be required at that time. Take a look at this site:
http://www.ydxlabel.com/ydxlabel.htm I haven't tried them yet, but they look like a good idea.
