Severe weather including high winds, lightning, heavy snow, extreme heat, and extreme cold creates construction hazards. Employers must adjust work practices and provide protection when severe weather occurs. High winds affect scaffolding stability, can cause equipment tipping, and can blow materials or workers. Wind speed restrictions are specified for various equipment; work must stop when wind speeds exceed limits. Temporary structures including barriers and bracing must be designed for wind loads. Lightning strikes are a serious hazard during thunderstorms. When lightning is close (within 6 miles), work involving exposed heights should stop. Shelters and protective structures must be available and used during thunderstorms. Metal structures and equipment conduct electricity; workers should not remain in contact during thunderstorms. Heavy snow increases structural loads on temporary structures including scaffolding. Snow and ice accumulation on walking surfaces create slip hazards. Snow and ice must be removed from work areas and pedestrian routes. Extreme heat creates heat stress and heat illness hazards. Work schedules should be modified to avoid the hottest parts of the day. Adequate water and shade must be provided. Heat illness symptoms including dizziness and confusion require immediate cooling. Extreme cold creates hypothermia and frostbite hazards. Protective clothing including insulation and wind protection is required. Work periods must be limited to prevent exposure effects. Heat lamps or shelters warm workers between work periods. Seasonal transitions create extended darkness (winter) or extended light (summer) that affect worker safety. Adequate lighting is required for work in darkness. Fatigue from unusual light cycles must be managed.