Published: Tuesday, September 8, 2026
By Meteorologist Mike Witcher | eastTNweather
Good morning and Happy Tuesday!
Hopefully you had a fantastic holiday weekend. We’re back at it this week, and while meteorological fall may be underway, summer isn’t quite ready to give up across East Tennessee.
Knoxville reached 89° Monday, compared with an average high of 85°. Most of the region ran above average, and that general trend is going to continue through much of this week.
The good news?
We’re not talking about the excessive heat we experienced last week.
The more interesting part of the forecast comes toward Friday and Saturday when our rain chances increase—and then there’s a potential pattern change showing up farther down the road.
Most of East Tennessee Stays Dry Today
We had some decent downpours Monday evening, including portions of West Knoxville and the Southern Valley, but rainfall was far from widespread.
Today should be even quieter.
An inverted trough responsible for some of Monday’s activity is shifting west, taking the better opportunity for showers with it.
I’ve added about a 10–20% chance for an isolated shower today, mainly around the Cumberland Plateau with perhaps a stray shower around the mountains.
For most of us?
Dry.
Don’t be surprised if you see one lonely shower on radar this afternoon, but widespread rainfall isn’t expected.
Upper 80s With Manageable Humidity
We’ve got an interesting temperature spread this morning.
Parts of the Northern Valley and Upper East Tennessee are starting considerably cooler, with temperatures around 59–60° in spots, while Chattanooga is starting closer to 73°.
Lower dew points farther north have allowed temperatures to fall more efficiently overnight.
By this afternoon, most of East Tennessee climbs back into the upper 80s, with a few lower 90s possible.
Heat index values should generally remain in the lower 90s, perhaps reaching the middle 90s in the Southern Valley.
So yes, it’s still warm.
But compared with those 100°+ heat index values from last week, this is much more manageable.
High Pressure Keeps Us Warm
A ridge of high pressure continues building across the region over the next few days.
That’s going to keep winds light, temperatures above average and widespread rainfall difficult to come by.
We’ll generally remain in the upper 80s to around 90° through much of the week, with overnight lows mainly in the 60s.
The ridge isn’t going to disappear immediately, but it does appear to flatten and weaken somewhat later this week.
And that’s where our forecast begins to change.
Cold Front Approaches Thursday & Friday
A trough begins digging toward the region later this week, helping push a cold front toward East Tennessee.
The front approaches Thursday into Friday, with rain chances initially increasing across the Cumberland Plateau, Northern Valley and near the Tennessee/Kentucky border.
Better coverage could then spread farther south and east Friday into Saturday.
But there’s an issue.
The upper-level winds are running nearly parallel to the frontal boundary.
That means the front doesn’t have a strong push to drive it quickly south through East Tennessee.
Instead, it may slow down or even stall somewhere around the region.
Exactly where that happens will have a BIG influence on who receives meaningful rainfall.
Friday & Saturday Offer Our Best Rain Chances
This is not shaping up to be a particularly wet week overall.
Most of Tuesday, Wednesday and at least part of Thursday look relatively quiet.
But Friday and Saturday currently offer our best opportunities for showers and thunderstorms.
That’s good news because we’re entering a traditionally drier portion of the year.
September begins our transition toward the driest part of the calendar, with October typically being East Tennessee’s driest month.
So some beneficial rainfall would certainly be welcome.
Just don’t interpret those increasing rain chances as an all-day washout.
We’ll continue fine-tuning the timing and coverage as the front gets closer.
The Big Question: Is Fall Air Coming?
Now let’s go above and beyond the seven-day forecast, because this is where things get interesting.
There’s disagreement between some of our longer-range forecast models.
The American GFS model wants to keep the ridge relatively strong over the eastern United States well beyond the seven-day forecast.
If that’s correct, East Tennessee remains warmer than average for quite a while longer.
But the European model has been showing something different.
It builds the ridge initially, then weakens it and allows a deeper trough to develop over the eastern United States.
If that scenario verifies, we could finally open the door to cooler temperatures, lower humidity and a much more noticeable early-fall feel.
It could also increase our opportunities for rainfall.
Right now, it’s too early to pick a winner.
Model guidance is guidance, not gospel.
But it’s absolutely something I’m watching.
What Does the Climate Prediction Center Say?
The Climate Prediction Center’s 6–10 day temperature outlook for September 14–18 continues to favor above-average temperatures across our region.
Farther into the 8–14 day period, however, that warm signal begins getting squeezed somewhat.
That’s another hint that the overall pattern may eventually become more favorable for cooler air trying to work south.
On the rainfall side, we’re generally looking at near-average precipitation initially, with some potential for a wetter pattern developing farther down the road.
So there’s certainly reason to keep an eye on the second half of September.
Bottom Line
TUESDAY: Mostly sunny and warm. Only a 10–20% chance for an isolated shower, mainly Plateau/mountains.
WEDNESDAY: Hotter and mainly dry.
THURSDAY: Still above average as our next front approaches. Rain chances slowly begin increasing.
FRIDAY–SATURDAY: Best opportunity this week for more widespread showers and a few thunderstorms.
BEYOND THE WEEKEND: Forecast confidence drops. Some guidance keeps us warm while other data suggests a trough could eventually bring a more noticeable taste of fall.
I’ll be watching that pattern closely over the next several days.
If you’re tired of the heat and waiting for that first crisp East Tennessee morning, we may finally have something worth watching on the horizon.
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I’m Meteorologist Mike Witcher.
Have a great Tuesday and welcome back to the work week!
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