Five usual sources, ordered by how strongly Savannah's own weather and housing record points at each.
Lifted or missing shingles
Wind folds a shingle back and breaks its seal; the next rain goes under it. From the ground you may see a bare strip, a flapping tab, or granules and tabs in the yard after a blow.
In Savannah: NOAA logged 83 days with 58 mph or stronger thunderstorm wind in the county since 2014, and a peak gust of 91 mph. That is #31 of 209 cities we cover.
An old roof wearing through
Shingles go brittle, sealant dries out and a second layer hides the real condition of the deck. When leaks appear in several rooms, the roof may be at the end of its life, not just one spot.
In Savannah: 55.6% of homes here were built before 1980 and the median home dates from 1978.
Heavy rain finding a weak spot
Exposed nail heads, a worn pipe boot or a low-slope section only fail when a lot of water arrives at once. If the leak shows only in downpours, look there first.
In Savannah: 7 days a year bring an inch or more of rain here, out of 47.8 inches in total.
Hail bruises that open later
A hailstone can crack the mat under the granules without a visible hole. The roof sheds water for a while, then leaks weeks or months afterwards, often in the first hard rain of the next season.
In Savannah: Hail of 1 inch or larger fell on 12 days in the county's NOAA record; the largest stone was 1.75 inches.
Flashing and seams
Water follows the metal around chimneys, vents, skylights and wall joints before it ever reaches a shingle. A stain that sits right under one of those points to the flashing or its sealant.
In Savannah: Savannah has about 8 freeze-thaw days a year, the expand-and-shrink cycle that pulls those joints apart. That is #183 of 209 cities we cover.