It is better to caulk when weather is warmer because most caulks go on easier.
Caulks also bond better and are likely to stay put longer when applied during warmer weather.
However, some caulks can be installed in cold weather. Check with retailers who handle a broad range of caulks. Warm surfaces to be caulked with a hair dryer to melt any surface ice and remove moisture from the surface. Sand the contact surfaces if possible to improve bonding. You are the 2563rd access to this page.