my son temperature lately has been 78.2 is that ok he is 15

Hello and thank you for sharing your question.

First I suggest that you check the accuracy of your thermometer.

Normal body temperature is 98.F, give or take 1 degree.  A body temperature lower than 95.F is considered dangerous.  This is why it would be impossible to anyone to live day to day with a body temperature of 78.2.F.

So your thermometer is probably broken and needs to be replaced in order to learn his true temperature.  If you do get a new thermometer and his temperature is lower then 95.F then visit his doctor immediately!

Faith