"water can travel surprisingly far from where it actually enters"
Exactly this. Had a leak last year that I swore was coming from the window frame itself. Turned out the flashing above had shifted slightly. Quick fix with a few nails and some sealant, hasn't leaked since. Always worth checking higher up first—saved me from wasting another weekend on pointless caulking.
Good catch on checking higher up first. Flashing issues are notoriously deceptive—I've chased phantom leaks myself, convinced it was the window seal, only to find a tiny gap in the siding two feet above. Glad you sorted it quickly; nothing worse than spending hours caulking only to have the leak reappear next rainstorm. Always satisfying when the fix turns out simpler than expected.
Totally agree—flashing can be sneaky. Did you check if the drip edge above the window was properly angled? I've seen cases where it was installed flat or even tilted inward slightly, causing water to pool and seep behind the siding. Also, sometimes the house settling shifts things just enough to open tiny gaps. Did you notice any cracks or shifts around the window frame itself? Glad you caught it early though... chasing leaks is never fun.
"Also, sometimes the house settling shifts things just enough to open tiny gaps."
That's a good point about settling, but I'm not entirely convinced tiny shifts would lead to noticeable leaks without other contributing factors. In my experience, minor settling usually doesn't create enough of an opening unless there's already some compromise in the sealing materials or flashing integrity. I'd lean more towards checking the caulking first—especially if it's been a few years since the last application. Caulk tends to degrade quicker than we realize, especially on south-facing windows that get more sun exposure.
One thing I'd add is to double-check your window's weep holes (assuming it's a vinyl or aluminum window). Sometimes debris or paint buildup can clog them, trapping water inside and forcing it out through unintended gaps. Had this happen once at my place; cleaning them out solved the issue immediately. Either way, good luck with this—water intrusion issues can be tricky and frustrating to pin down.
Good points here, but I'd also suggest checking your weather stripping closely. I had a similar issue recently—thought it was caulk at first, but turned out the weather stripping had flattened out and wasn't sealing properly. Replaced it and no more leaks. Also, double-check the window alignment itself...sometimes even slight misalignment can cause weird water paths. Hope you figure it out soon, leaks are super annoying.
"sometimes even slight misalignment can cause weird water paths."
That's a great catch about alignment—I've seen that happen a lot. Did you notice if the window closes evenly all around, or does one side seem tighter than the other? Sometimes even a tiny gap or uneven pressure can redirect water in unexpected ways. Also, have you checked if your drainage holes are clear? I once had a client whose issue turned out to be clogged weep holes...water backed up and found its way inside.
Yeah, alignment's definitely a biggie, but honestly I'd check the flashing too. Had a similar issue last spring—thought it was caulk at first, but turned out the flashing above the window had warped slightly. Water was sneaking behind and dripping inside. Quick fix once I spotted it, but drove me nuts until then...worth a look before you redo all your weather stripping or caulking.