Using low beam headlights in heavy rain is essential for maintaining visibility and safety on the road. Heavy rain can create conditions where visibility is significantly reduced due to the precipitation, and high beam headlights can cause glare as the light reflects off the water droplets, making it even harder to see.
Low beam headlights provide adequate illumination of the road directly in front of you without producing that glare, allowing you to see the lane markings and any obstacles more clearly. They also help other drivers see you better without reflecting light back into their eyes, which can happen with high beams.
Fog lights, while useful in certain conditions like fog or snow, do not necessarily provide the best lighting for heavy rain, and there are circumstances when their use is inappropriate or ineffective. Similarly, not using any headlights in low visibility conditions such as heavy rain would be dangerous for you and other road users, as it makes your vehicle less visible and compromises your ability to see the road. Therefore, utilizing low beam headlights is the safest and most effective option in heavy rain.