Extreme Heat Warning: Record-Breaking Temperatures & Essential Safety Tips

The first major heatwave of 2025 is surging across the American West, and the National Weather Service (NWS) has escalated alerts to an “Extreme Heat Warning” for portions of California’s Central Valley, the Mojave Desert and southern Nevada from Friday through Saturday. Afternoon highs are forecast to spike into the 105-110 °F range, with Las Vegas projected to flirt with 109 °F and Death Valley likely to exceed 115 °F. In Northern California, a parallel Heat Advisory covers much of the Bay Area. Temperatures are expected to top 100 °F in far-eastern Contra Costa and portions of the Santa Clara and Sacramento valleys, marking the region’s first triple-digit readings of the year. Coastal zones will stay milder, but the rapid warm-up after an unusually cool spring raises the risk of heat illness for anyone unaccustomed to mid-season scorchers. Why so intense, so early? A stubborn upper-level high-pressure dome—sometimes called a “heat dome”—is locking in cloud-free skies and sinking air that compresses and bakes the surface. Scientists warn that these blocking patterns are becoming more frequent as the planet warms. A new five-year outlook from the World Meteorological Organization projects that every year through 2029 is likely to be at least 1.5 °C (2.7 °F) above pre-industrial averages, virtually guaranteeing more record-smashing heat events. Understanding the alerts • Heat Advisory: Conditions can be dangerous for sensitive groups (elderly, young children, outdoor workers). • Excessive Heat Warning: Life-threatening for anyone without access to cooling. • Extreme Heat Warning: A newly emphasized tier reserved for situations where nighttime lows stay hot, heat indices soar well above normal, and widespread health impacts are likely. The NWS now issues these warnings when models show at least a 50 % chance that heat-risk thresholds will be exceeded for two consecutive days. How to stay safe during an Extreme Heat Warning 1. Hydrate early and often—don’t wait until you’re thirsty. 2. Limit outdoor activity to before 10 a.m. or after 6 p.m.; reschedule strenuous work if possible. 3. Use air-conditioned spaces. Local governments are opening cooling centers; check municipal websites or 2-1-1 hotlines for locations. 4. Never leave children, pets or vulnerable adults in parked vehicles, even for a few minutes. 5. Check on neighbors, especially those living alone or without reliable cooling. 6. Know the signs: heat cramps, then heat exhaustion (dizziness, heavy sweating, nausea), and finally heat stroke (altered mental state, no longer sweating). Call 911 if heat stroke is suspected. Wider impacts to watch • Power demand: Utilities in California and Nevada are already forecasting peak electricity loads and may issue voluntary conservation calls. • Wildfire risk: Desiccated grasses from a wet winter are primed to ignite if gusty outflow winds accompany the heat dome’s eventual breakdown. • Infrastructure stress: Asphalt can soften near 140 °F, increasing the chance of roadway buckling, while rail lines may impose slow orders to prevent track warping. Forecasters expect a brief cooldown early next week as the ridge shifts east, but long-range models hint at additional heat surges in June. Public-health officials emphasize that early-season events are often the deadliest because bodies have not yet acclimatized. Staying informed and prepared during this Extreme Heat Warning can mean the difference between discomfort and a medical emergency.