textproduct: Louisville

KEY MESSAGES

* Unseasonably hot weather will continue for much of the area through at least Sunday. Barring any early day thunderstorms, heat indices will top out in the mid 90s to around 105 (highest southwest) each afternoon.

* There is a 30-50% chance (highest northeast) for showers and storms late this afternoon and evening, with slightly lower chances tomorrow. Locally damaging wind gusts, frequent lightning, and heavy rainfall may accompany the strongest storms.

* A weather system will bring higher rain chances (50-70%) Monday into Tuesday, followed by a cool down to more seasonable temperatures (highs in the 70s, lows in the 50s) by the second half of week.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 332 PM EDT Sat Sep 19 2026

It has been a dry but hot day for our area so far, with temps climbing into the lower 90s, and isolated storms noted all around our area. SPC maintains the Marginal Risk for severe storms through this afternoon and evening. More details below.

===== Unseasonably Hot Temperatures Continue =====

KY Mesonet shows temperatures in the 90s across the region, with Butler county currently reporting 100F over a 61F dewpoint. Definitely seeing some mixing going on this afternoon to lower those dewpoints some, but most heat indices are in the upper 90s to lower 100s. A similar forecast is expected tomorrow, with the entire area at least reaching the low 90s. While we may not reach advisory criteria again tomorrow, will plan to extend the Heat Advisory one more day due to potential impacts given the temps in the middle of September. We are nearly 10-15 degrees above normal. The record max temp for both today and tomorrow is 96F, so those records will be in jeopardy.

===== Marginal Risk for Severe Weather Today =====

There is a low-end risk (level 1 of 5) for some isolated to scattered strong to severe storms this afternoon and early evening. GOES satellite imagery and LVX hi-res shows a boundary sneaking into our area from central IN, which will be the focus area for storms to fire off from. Given the strong heating today, we've been able to realize over 1500 J/kg of MLCAPE, though wind shear is very weak. Model soundings show large CAPE profiles, with DCAPE around 1000 J/kg, and PWATs around 1.6". There is a chance for scattered storms to pop up in this environment, which would be slow moving heavy downpours, with damaging wind gusts and frequent lightning as the main concerns.

The Marginal Risk for tomorrow has been trimmed to now include mainly our counties north of I-64. Coverage for tomorrow looks to be even less that what is possible today, so mainly a stray storm chance for Sunday.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 332 PM EDT Sat Sep 19 2026

===== Monday - Wednesday =====

Sfc low pressure will be sitting across the area on Monday, which will support at least some isolated to scattered showers and storms across the area. In addition to those chances, Monday features quite a tricky temperature forecast, with a north-south gradient expected on where that sfc low sits. There is potential for us to see temps in the upper 70s near Madison IN, to lower 90s across south-central KY Monday afternoon. Any severe potential will be limited to the south side of the low where better heating will be, so overall severe risk appears low at this time.

For Tuesday and Wednesday, we'll be in a post-frontal cooler airmass with an upper trough overhead, which will bring a welcoming change in temps to the region. Highs on Tuesday still could be split north to south, with mid-70s north of the WK/BG Pkwys, and mid--80s to the south. However, by Wednesday, we begin to see more fall-like temps with highs in the 70s and overnight lows in the 50s. We'll still have some precip chances during this time due to broad lift from the trough, but a gradual exit to the east is expect by Wednesday night.

===== Late Next Week =====

The upper pattern will amplify over late next week with the upper trough deepening into an upper low over the East Coast, and ridging building across the Central Plains. This will place the Ohio Valley in a more persistent NW flow, which will result in amplifying our cooler pattern. The result could be more days with highs in the 70s and overnight lows in the 50s. Dry weather is expected through the end of the week with sfc high pressure moving across the Great Lakes region.

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 134 PM EDT Sat Sep 19 2026

VFR conditions are ongoing across the area this afternoon with light winds generally from the SW. We'll see clouds increase through this afternoon and evening from the north, with lower chances for some scattered storms this afternoon mainly for LEX/RGA. It's possible HNB/SDF may need an amendment to mention precip, but confidence is not high enough to mention any. Otherwise, dry weather expected tonight with VFR tomorrow.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory until 8 PM EDT /7 PM CDT/ Sunday for KYZ023>028- 053-061>063-070>076. IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Sunday for INZ083-089.