I think people need to observe the manufacturer's specifications for operating in extreme temperatures. The electronic components used in the radio gear determines what the limit of operation is. For example, most commercial spec parts operate fine from 0C to +70C. If you operate the radio beyond the manufacturer spec then you could open a can of worms insurance wise and we all know how lovely insurance people are... :-)

Crystals in particular are very sensitive to temperature change.

Just my $0.02 worth...

Check your instruction manual that came with your radio. It should specify the operating temperature range. If it doesn't, contact the manufacturer.

Cheers
Jason.