It all depends on where you are. I think Jim L has the basics right.
One disclaimer- if you are in Pacific NW temperate conditions on both
ends might not mean as much if shipment is likely to go through ND and
it's -6 there.

I'm in southern NY and before doing a West Coast shipment in winter I
usually check temps in Chicago (or Phoenix and Houston in summer). If
I know shipper uses styro, I don't worry about low temps of 20 along
route. Cardboard shippers are less forgiving.

Overall cold is only an issue if you think there is a chance bottles
will go below 25 for extended period, causing freezing that might
cause seal to fail. Shorter cold might lead to harmless precipitates.
Generally I worry much more about heat than cold.
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Hi Dale,
I'm in the Philly area so it will only be a problem on the shipping end. I
went
ahead with the order and asked the shipper to ship on Tuesday, when it will
be a little warmer up there.

Regards,
Jon