Does the cold impact my welds?
Absolutely! As one would expect, cold air causes the welds to cool faster and creates surface moisture formation. Both of these make the welds more susceptible to cracking. To avoid this, preheat the material you are welding to at least 50 F with your torch. Additionally, if it is a delicate weld and particularly windy, postheating the welds may also be wise. Rapid cooling causes stress in the welds and may cause them to deform or crack. Postheating the welds can release these stresses and help the weld to cool in a more controlled manner. Also, try to evaporate any condensation on the material that you are about to weld. While it’s impossible to completely remove moisture, especially in places such as my own lovely Seattle, making sure that there isn’t water pooling or sitting in beads on the location you will be welding is still important. Reduce your speed while welding to give the weld more time to heat up. Also turn up the heat on your torch to compensate for the lower temperatures. Modern welding manuals also advise that you tack the metal sporadically, every 3″ or so, as the sharp difference between the hot and cold metal can cause deformation.
What about when I’m outdoors?
There’s a joke for motorcycles that is also appropriate for welding: There is no such thing as bad weather, just insufficient gear. With the proper gear and precautions, you shouldn’t have any issues. If you are outdoors, check the weather in advance and do periodic test welds. The time of day, cloud coverage, wind speed, and wind direction can all dramatically impact temperature and therefore your welds. Portable cover is also useful if you have access to it, wind shields in particular are especially useful as there is no really good way to combat wind except shields. One exception to the “no such thing as too cold” rule for our American customers to keep in mind: some state and federal organizations do require minimum temperatures for welding. So if you are doing a job for them, keep that in mind and check the thermometer.