I have been running successfully Meteorologist 2.0.4 and decided to try 3.0.4. Upon launching it immediately gets killed by the system:
5/31/17 9:04:47.836 PM com.apple.xpc.launchd[1]: (com.apple.xpc.launchd.oneshot.0x1000001d.Meteorologist[7128]) Service exited due to signal: Killed: 9
I removed all com.heat.xxx.plist files but still have the problem.
I installed 2.0.4 into a 10.11.6 system using the default weather location then installed 3.0.4 and did not experience any issues other than the code signing (right click and select Open to get around that).
Try rebooting or issuing this terminal command to kill the cached preferences: killall -u $USER cfprefsd