Some optometrists and ophthalmologists insist that wearing contact lenses in the rain is fine if you take precautions to not get water in your eyes. However, others said people need to avoid wearing contact lenses in the rain because there are several risks associated with getting water in your eyes. Removing contact lenses before any activity involving contact with water, including showering, using a hot tub, or swimming.
The rainwater is actually polluted, so it'll harm our eyes when there's still some foreign matters in our eyes. The foreign matter I mean are contact lenses.