1000 Joules
Friday, September 18, 2026 · 7:03 PM
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Very hot and humid conditions with triple digit heat indices continue. A Heat Advisory is in effect through Sunday for most of Middle Tennessee. Low rain chances mainly for the Plateau this weekend with a low chance for strong thunderstorm winds Saturday. Low to medium rain chances spread area-wide Monday and Tuesday. Cooler temperatures arrive next week, but still remaining above normal. Late morning temperatures already ninety degrees Four consecutive days breaking nineteen fifty-three The ridge retreats southwest but the heat is locked in Along and east of Interstate sixty-five Heat indices reaching one hundred five Atmospheric instability built on dry surface air Downburst potential in the steep lapse rates Convective energy primed to explode DCAPE values over one thousand Joules per kilogram Waiting for the upper troff to collapse the dome ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES ONE THOUSAND JOULES
The forecast discussion
KEY MESSAGES
Updated at 656 PM CDT Fri Sep 18 2026
- Very hot and humid conditions with triple digit heat indices continue.
A Heat Advisory is in effect through Sunday for most of Middle Tennessee.
- Low rain chances mainly for the Plateau this weekend with a low chance for strong thunderstorm winds Saturday.
Low to medium rain chances spread area-wide Monday and Tuesday.
- Cooler temperatures arrive next week, but still remaining above normal.
SHORT TERM
(Rest of today through Saturday) Issued at 1120 AM CDT Fri Sep 18 2026
Another day of potentially record-breaking heat as late morning temperatures are already at 90 degrees in some spots.
Ridging is beginning a slow retreat southwest, but it's influence will continue through Monday.
Nashville's high temperature record today is 99 (1953); the forecast high today is 99. If we reach that, today would make 4 consecutive days of either breaking or tying the high temperature record.
Highs will remain around the same values through this weekend with warm overnight lows in the low to mid 70s west of the Plateau.
There is another very low chance for an isolated storm this afternoon, but as with similar days, most will remain dry.
As the ridge pulls west, a weak shortwave will be allowed to ride across the ridge tomorrow, bringing a higher chance for scattered afternoon thunderstorms mainly for areas along and east of I-65. Widespread severe weather is not anticipated, but a few strong to severe wind gusts could occur in the strongest storms given steep low-level lapse rates and DCAPE values over 1000 J/kg.
LONG TERM
(Saturday Night through next Friday) Issued at 1120 AM CDT Fri Sep 18 2026
The heat will stick with us through the start of next week.
A Heat Advisory remains in effect through Sunday for heat indicies of 105+.
A trough will move through Tuesday that will allow for better, more widespread rain and thunderstorm chances to return to the forecast.
The troughing pattern looks to remain in place through the week with long range guidance hinting at a strong upper low dipping down over the southeast.
Should this happen, we would finally see a pumpkin spice-esque change in our temperatures.
The NBM is also optimistic with highs in the upper 70s to low 80s by the end of next week and overnight lows in the upper 50s to low 60s....Yes, 50s and 60s!!
We'll continue to monitor 500mb long range trends and keep our fingers crossed that this pattern shift is on the way.