The violins are presently stored in a closet in which the
temperature just now was 49.5 degrees F. On the floor of the
closet are two heating pipes filled with water. The 
temperature in these pipes is controlled. When the outside
temperature is well above freezing the water in the pipes is
stationary and unheated. When the outside temperature is between
29 and 34 degrees, unheated water, its temperature closely monitored
is pumped through all the pipes in the house. It's temperature
ranges between 48 and 52 degrees. When the outside temperature
is below 29, the water circulating on the floor of the closet
is heated by the oil burner to a range of 66 to 69 degrees.
Under these circumstance the temperature in the house, - and I
assume also in the closet ranges between 46 and 52 degrees.
I have not measured the humidity in the closet, but given the
relatively constant temperature, the humidity may be presumed
to stay relatively constant as well.

On the Internet, I reviewed several articles about storage of violins
in winter. The chief concern is for below freezing temperatures
and large rapid swings in humidity. Neither of which is a risk
where the violins are presently stored.

I conclude that the violins, in their present storage locations are probably 
adequately protected against swings in temperature and humidity. 
I believe it would be potentially harmful to move the violins stored
at 50 degrees into a 70 degree environment with normal humidity,
inasmuch as until the wood itself has warmed up it will cause the
70 degree normal humidity to become much higher. The wood must be
warmed in an environment of gradually rising temperature and humidity.