Happy Monday!
Welcome back to the workweek, East Tennessee! As your local meteorologist, I’m rolling out the latest weather update for Monday, July 21, 2025. We started the day off with some patchy dense fog, especially where we saw rain on Sunday and through the overnight hours. It’s been feast or famine lately, hasn’t it? It’s a very muggy start, with that ‘air you can wear’ kind of feel thick in the air. This easy-to-grab blog dives deep into today’s forecast for Knoxville, Chattanooga, and the Great Smoky Mountains, then lays out the rest of the week and weekend in detail—so let’s jump in and get ready!
Today, Monday: Foggy Start, Hot Afternoon with Storm Potential
We’re kicking off with that patchy dense fog, lingering where Sunday’s rain left its mark, making for a hazy, muggy morning. Temps are in the 70s, with dew points adding to that sticky vibe, but the fog will burn off as some sunshine breaks through. The heat is back with us today—lunchtime temps will climb into the 80s, and afternoon highs will hit the low 90s. Oh, and that heat index will push 100°F once again, so it’ll feel like a steam bath out there—stay hydrated and find shade! Now, let’s talk rain chances. We’ve got a better shot at rain today, especially in areas that haven’t seen much lately—that’s the hope, anyway. A front just to our north, sliding in from the northeast, is a backdoor cold front. It won’t cool us off much, but it’ll slightly lower the humidity and aid in storm development, especially with another upper-level wave swinging through. While the Storm Prediction Center isn’t flagging a severe weather threat, we could see strong gusty winds with any storm that fires up. With a water-loaded atmosphere, expect torrential downpours that could spark a localized flash flood threat—the Weather Prediction Center has us under a Level 2 risk today. The best timing for these storms looks to be after 3 PM, lasting through 8-10 PM, so plan your evening accordingly. Use the eastTNweather app to stay on top of it, with its Interactive Radar showing past, current, and future views!
The Rest of the Story: Tuesday Through Sunday
Looking ahead, Tuesday through Friday will shift gears a bit. We’ll see slightly drier air move in, with less precipitable water in the atmosphere, cutting down the chance for showers and storms significantly. I’d expect just a few afternoon storms, mostly isolated along the higher terrain like the Cumberland Plateau and Smoky Mountains, at this point. Highs will hold steady in the low 90s all week, with that heat index lingering in the low 100s—still warm, but the humidity dip might ease the edge a little. That backdoor cold front will play a role, keeping storm chances low but not eliminating them entirely.
For the weekend—Saturday, July 26, and Sunday, July 27—I’ve bumped up the rain chance from 30% to 40%. Right now, it looks like we should see better coverage of afternoon showers and storms both days, a nice change after this week’s drier trend. However, we’re still 6 and 7 days out, so this is a preliminary call—check back as I refine the forecast closer to the date. The setup could involve lingering moisture from that front mixing with summer heat, but it won’t be a total washout. Highs should stay in the low 90s, with heat index values possibly creeping back toward 100°F if humidity builds.
Beyond this week, the pattern suggests a continuation of that ridge influence, keeping heat and humidity in play. The Climate Prediction Center hints at average to slightly above-average rainfall, with isolated afternoon storms persisting into late July. No major cold fronts are on the horizon, so we’re locked into that classic East Tennessee summer groove—hot days with occasional wet breaks. For Knoxville locals, Chattanooga outdoor fans, and Smoky Mountain visitors, this helps you plan and stay safe.
ABOVE AND BEYOND THE 7 DAY FORECAST
Extended Outlook: More Heat, Average Rain Chances
Beyond the 7-day forecast, the pattern looks to hold steady with above-average heat and near-normal rain chancesaccording to the latest guidance from the Weather Prediction Center. So we may not get a ton of relief from the heat anytime soon — but at least we’re not trending bone-dry.
Why This Weather’s Happening
That foggy, muggy start comes from Sunday’s rain and high dew points, with a backdoor cold front and upper-level wave stirring the pot today. The front won’t cool us much but will tweak humidity and spark storms, while the water-loaded air fuels those torrential downpours and flash flood risks. The drier air midweek eases storm chances, but the building ridge next week will crank up the heat again. Stay alert!
eastTNweather: Your Go To Weather Source
The eastTNweather app is your go-to for East Tennessee weather. Launched in October 2023 after 20 years at WBIR, it delivers three daily video forecasts, a live morning chat, and updates on MikeWitcherTV and ETNWeather. Free on Roku, Amazon Fire, eastTNweather.com, and the app, it’s a robust tool that travels anywhere in the country, giving you everything you need to stay informed locally and beyond. Its Interactive Radar is key for tracking storms—download it today!
Stay Connected with eastTNweather
I’m here to keep you in the know and safe. Pop over to eastTNweather.com, grab the app, or follow me on social media for the latest on today’s fog and the week’s forecast. Have a great Monday, thanks for checking in on the eastTNweather platform, and let’s make this week awesome together!
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Meteorologist Mike Witcher
eastTNweather – Weather When You Want It