Weather agencies across the Southwest have issued an Extreme Heat Watch from Wednesday through Friday, warning that temperatures in the lower deserts of Arizona and southern Nevada, including Phoenix and Las Vegas, are expected to climb into the 110°–115°F range. The National Weather Service says the conditions will create widespread Major HeatRisk and pockets of Extreme HeatRisk, increasing the likelihood of heat-related illnesses and straining regional power and health systems. Forecasters advise residents to limit outdoor activity, remain hydrated and avoid leaving children or pets in vehicles. Nighttime lows are projected to stay in the upper 80s, offering little overnight relief. The Occupational Safety and Health Administration recommends rescheduling outdoor work to early morning or evening hours and providing frequent rest breaks in shaded or air-conditioned areas. Elsewhere in the West, Denver is beginning the week in the low to mid-90s with a chance of afternoon storms and a risk of severe weather on the northeastern plains, while the San Francisco Bay Area experiences its coolest day of the week on Monday before temperatures rise later in the week.