To piggy back off of LordOfAngels,
Do you have Automatic Date & Time turned on? You can check this by going into Settings -> Date & Time.
Make sure you also have Automatic time zone turned on as well.
If that doesn't work, try reconnecting to your carrier's network.
in Settings under "Wireless & Networks" tap More. Then tap Mobile Networks -> Network Operators
Wait for it to load and select your carrier. That should sort you out.
If the above doesn't work, try reflashing whatever ROM you're on. If you're on Stock, you might want to bring your device in a carrier's store because that should not be happening if you have automatic date & time and you haven't altered your phones firmware.