There are two things to consider when repairing a roof in the rain, the first is the safety of the roofers who are carrying out the repairs as a roof will be extremely slippery and dangerous when wet. In addition to this, the repairs may not always be as effective or last as long if the roof is wet. Most professional roofing companies will still carry out the repairs for you in wet weather as they will have the safety equipment to make sure their team are safe, as well as understanding that not carrying out the repairs quickly will likely cause more damage to the property in the short and long term.