Santa Ana wind season
From about October into the winter, dry winds pour down through the Cajon Pass and off the mountains at speeds that lift ridge caps, crease shingle tabs, strip brittle felt from under tile, and drop tree limbs onto roofs. The north and east slopes and the leading edges near the ridge take the worst of it. Houses on the foothill edge of Highland, north San Bernardino and north Rialto see it first.
The damage is often invisible from the ground until the next rain finds it.
Winter storms
Pacific fronts bring heavy, sometimes sudden rain, occasionally with hail in the higher areas. Wind-driven rain gets under eaves and into any flashing that the fall winds opened. Debris washed into valleys and gutters dams the water and pushes it under the roofing. Flat commercial roofs pond and find every open seam.
This is when the phone rings, but the cause was usually set up weeks earlier.
What I do during the event
Stop the water. A tarp battened over the damaged area, buckets and plastic in the attic if the ceiling is at risk, and a quick photo record before anything is disturbed. I do not do permanent repairs on a wet roof; it is unsafe and the materials will not bond. The tarp buys the time to do it right.
If it is still raining, keep everyone off the roof, including yourself.
Documentation for insurance
Photographs of every damaged area, the debris that caused it if any, the interior damage, and the temporary measures. A written scope of the permanent repair with the cause stated plainly. Insurers respond to clear evidence and a clear scope, and they resist vague claims. I write reports that adjusters can use.
Keep your own photos too, with dates, from the moment you notice the problem.
The permanent repair
Once dry: creased and lifted shingles replaced, ridge and hip caps reset on a mechanical system, cracked tiles swapped and the felt beneath repaired, torn flashings replaced, valleys cleared and re-metaled if needed. On a roof that was already near the end, I will say whether the storm has tipped it into replacement territory rather than patch what will fail again.
Then the fall check the following year, so the next wind season finds a tight roof.