Problem with my '92 Honda Accord engine thermometer...?
 

So I am not very knowledgeable when it comes to cars and am unsure what this problem could be. Whenever I am sitting at a stoplight or idling with the engine running, the engine thermometer gauge begins rising and I can smell burning rubber. As soon as I begin driving again, the thermometer goes down to normal and the smell goes away. Does anyone know what's going on? Thanks in advance for your help!