Considering the fact that it is summertime and most of the country is experiencing heat wave like conditions this will affect the cold water temp coming into your'e home. Well water is usually not affected because of it's depth or until the warmer water is flushed out of the pipe.
If you don't think this is the problem then we would need more specifics because it is possible you could have a cross connection i.e. bad solenoid on washer etc.