There are a number of preemptive tasks that can be done to keep a roof well-maintained, and roof leak detection is perhaps the most important one. A leaky roof will cause all kinds of damage and result in repairs that will cost several thousands of dollars.
There are any number of sources of leaks in a roof: a poor roofing job, damaged roofing materials, weatherization of seals around vents, and damage from animals. While the least likely to be problematic when it comes to a leaking roof, even soffit vents can be a source of leaks.
Evaluate Your Roof
There are a number of fixtures and features on a roof that can contribute to the roof leaking. Features such as chimneys, vent covers, skylights, or roof lights can all be culprits to a leaky roof. All of these features sit against or on top of the roof, and if they are not integrated into the roofing materials properly and properly sealed, they can be prone to leaking.
If you suspect that any of these items is the source of the leak, take some times to inspect it and the surrounding materials. Replace any that appear damaged or worn, and reseal around the fixtures.
A waterproof seal around any fixture on the roof is critical. Any feature in the roof will attract water as it will either offer a place to pool, to run off, or, in some cases, to run in. Silicone caulk can be all it takes to properly seal vents, skylights, and about any other item on your roof that may be prone to leaking.
While they are the least likely to be the culprit of a roof leak, soffit vents can certainly be the source. Typically, because of the vent's location underneath the roof's overhang, the vents are protected from moisture entering the attic spaced through the vent. Rain doesn't usually fall up. In the event of severe weather, however, water and moisture can still enter into these vents, resulting in wet insulation in the walls of the home and wet drywall in the interior.
This can contribute, particularly over time, to extensive damage and the necessity of replacing some significant features on the home. The further away the soffit vents are from the exterior wall of the home (which of course is limited by the span of the roof), the less likely they are to be a source of water entering the attic.