RE: Jets and cold weather condition
Cold temperatures are not a problem for your electronic or turbine or structure of the plane, until this not to low. All my plane are on my cellar and actually it's 10°C or lower...
The problem is more the transition between "hot" temp and very low temp, that could cause structural problem because of qwick dilatation. Another problem is the water, as said by Dubd.
The only parts that need positive temperature are the batteries, so keep them in your house.