The warning went up at 1:04 AM and runs until 9 PM this evening. The issue isn't just the heat index hitting 100 — it's that overnight lows are only dropping into the lower 70s, so bodies don't get a real chance to recover before the next round of heat builds. NWS is flagging that as the real risk: cumulative heat stress that raises the odds of heat exhaustion and heat stroke the longer it drags on.
Friday looks like more of the same at first — sunny, a high near 97, heat index up to 101 — before a cold front tries to break the pattern. There's a slight chance of showers and storms Friday night between 8 and 10 PM, and behind that, temperatures actually ease off. Friday night's low is 71, but Saturday tops out near 90 and Saturday night drops to 69, the first real overnight cooldown in a while.
Sunday climbs back to 91 under mostly sunny skies, so this isn't a one-and-done heat break — just a dip. For today, though, treat it like the warning says: dangerously hot. If you've got outdoor plans, parks trips, or anything at the airport that means standing around on pavement, midday through late afternoon is the stretch to avoid. Check on anyone who can't cool down easily overnight, since that's exactly the scenario NWS is warning about.