Urethane and water
Polyurethane windshield adhesive cures by reacting with moisture in the air, which sounds like rain should help. It does not, because the problem is not humidity — it is liquid water on the surfaces being bonded.
A wet pinch weld means a film of water between the adhesive and the metal. The urethane bonds to the water rather than to the flange, and the bond fails — sometimes immediately, more often quietly over months as it lets go.
Dust and cold matter too
The same is true of a dusty flange or one with sap on it. Prep is about giving the adhesive clean dry material to grip.
Very cold weather slows cure enough that safe drive-away time stretches considerably; that is a delay rather than a barrier.
What we do instead
If you have a garage, a carport or covered parking, the job goes ahead as normal — a covered space is all that is required, not a heated one. Plenty of our wet-weather work happens in apartment parking structures.
If you do not, we reschedule. That is a genuinely better outcome than a windshield that leaks in November and needs doing twice.
What to watch for
A mobile company that fits a windshield in open rain is either using the weather as an excuse to rush or does not understand the chemistry. Neither is who you want bonding a structural component to your car.
Need this done rather than explained? There is no shop to drive to. We come to wherever your car already is — your driveway, your workplace car park, an apartment lot, or the side of the road it stopped on — anywhere in greater Sacramento, with no call-out fee and no mileage charge. Give us the year, make and model and you will have a firm price before the call ends.