Was this a oral (mouth) temperature reading?
Is he sick? Did he feel hot? Or the chills?
Did he recently have something cold to drink?
Since you are offline at the moment, generally 95 degrees or below is considered hypothermia:
Oral temperatures tend to run on the lower side, than say a true temperature (rectal), and also if the temperature was taken close to when he may have had a drink of cool water/soda, etc, it also could have influenced the temperature reading.
Regardless, if this is a true reading, the simplest thing is to bundle up. If this is a possible reaction to an infection (e.g. he has other symptoms) keeping a close eye on the temp and other symptoms, if worsens, to take him to the pediatrician.
But if I have been outside on a cold day and gotten a little chilly, my temperature could run a little lower than normal, like the temperature he has.
The average temperature, when taken in the mouth, is 97.6
95.7 is lower than average, but is probably still considered near normal and not hypothermia (below 95).
A temperature of 100.4 is higher than normal, and probably would be considered a temperature, which could be caused by illness, or hot weather / exercising / hot baths, etc.
Of course, both of these temperatures could have been affected by recent cold or hot drinks.