Comment by kragen

No, it wasn't because the surrounding weather was slightly different. The surrounding weather was exactly the same. The air currents were slightly different because a warm rock in Karnataka thermally emitted a photon 13 years earlier that it didn't emit on our timeline. (This happens, as far as we know, completely at random, without any cause; cf. https://en.wikipedia.org/wiki/Quantum_indeterminacy.) That was enough to cause the global atmospheric system to diverge enough that the mosquito stung someone else.

The findings of chaos theory are counterintuitive, but they are absolutely fundamental to how our universe works.