Very hot connection at rusty ground clamp by water meter
You have a lost neutral.  Turn everything off NOW!

Your electricity is served to you as two "legs" with 240V across them -- and a center-tap called "neutral".  This gives you 120V between a leg and neutral. 

Water heaters and A/C units take the 240V directly and ignore the neutral.  Any 120V load, however, connects between a hot leg and neutral to give it only half the voltage - 120V. 

If something goes wrong with the neutral, crazy stuff happens. Each 240V leg has several 120V loads between the leg and neutral.  If the neutral is lost, nothing "pegs" those voltages at 120V anymore!  They are still 240V apart, and the two legs will add up to 240, but they could be 90 and 150 volts.  (those unequal voltages, adding up to 240V, is the sure sign of this, if you have a voltmeter.) 

That will start fires.  So why hasn't it?  

Neutral is called that because it's also bonded to the water pipe/ground inside your main panel.  The intent is emergency use only.  The transformer on the pole, also bonds its neutral terminal to a grounding rod at the base of the pole.  Current is using this path instead (via dirt) because your neutral wire is broken.  This problem will get much worse.  

Dirt is not a reliable conductor, and if the resistance goes up, or your load goes up, your voltages could start getting wobbly and start blowing things up. That's why you need to fix it right away. 

Also, this current flowing through your water pipe is corroding it.  Normally no current should flow through the ground.  It shouldn't be getting warm. 

A lost neutral is a power outage, call it and report it as such!  The problem might be inside your service panel, but they will probably tell you if it is.  

Also, stay away from the clamp unless your main breaker is off.  It is (wrongly) part of the electrical circuit, and if disconnected or messed with, it can shock you.