Which weather conditions should pilots avoid during helicopter flight?

Pilots should avoid thunderstorms and heavy rain during helicopter flight due to the severe hazards these conditions present. Thunderstorms can produce dangerous phenomena such as severe turbulence, lightning, hail, and low-level wind shear, all of which can significantly impair aircraft control and safety. Heavy rain can also reduce visibility to dangerously low levels, making navigation and obstacle avoidance challenging. Additionally, sudden downbursts associated with thunderstorms can create conditions that are detrimental to helicopter performance. Therefore, avoiding these conditions is crucial for maintaining safety during helicopter operations.