My landlord turns off the heat every year on April 15th. We live in Pa and it still gets cold at night. Is there a temperature limit to where they must have the heat on? Who can I report my landlord to?

First where in PA can make a difference as some cities may have rental code boards, but in general code enforcement would be a first stop if there are local or state codes, Or they could tell you if there are specific boards.

What are the temp it is getting, is this rental under any section 8 rental( or any of the units section 8.

Statutes in PA require heat to available Oct 15 to April 15 unless local law supercedes that.
A cruel landlord indeed. Can you move?

Example locally:
The City of Harrisburg:
Provide heat between October 1st and May 15th at a minimum of 65° between 6:30 AM and 10:30 PM; 60° during the night and when the temperature is below 0° unless otherwise provided by lease.

Statutes in PA require heat to available Oct 15 to April 15

Sounds like the landlord knows the law, unlike you. Your choice would appear to be to move when your lease is up.

In the meantime you might look into space heating with an electric heater or kerosene unit. Sengoku La LTD HMHC2230 Convection Kerosene Heater (http://www.google.com/products/catalog?q=kerosene+heater&hl=en&prmd=imvns&resnum=2&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1272&bih=684&wrapid=tlif133562390060810&um=1&ie=UTF-8&tbm=shop&cid=7091436876744717981&sa=X&ei=9wCcT5CSKJCC8QSe48CmDw&ved=0CGwQ8gIwAA#)