textproduct: Louisville

KEY MESSAGES

* Heat Advisory remains in effect through this evening.

* Unseasonably hot temperatures continue with highs in the mid to upper 90s and heat index values up to 105 degrees.

* Weak front brings low end (20-30%) rain chances on Friday

* Better chances of rain return early to mid next week.

SHORT TERM /THROUGH TONIGHT/

Issued at 430 AM EDT Thu Sep 17 2026

Today, upper high pressure, centered over the Mid-Mississippi Valley, extends over the Lower Ohio Valley with zonal flow stretching from the Upper Plains east through the Great Lakes and off into the Atlantic. At the surface, a west to east oriented front remains to our north with high pressure north of that. Another area of high pressure remains over the Southeast, keeping light WAA and high dew points in place over southern Indiana and central Kentucky, south of the front. Highs are once again expected to climb into the mid to upper 90s in most areas. Parts of the Bluegrass and southeast Indiana may only see the low 90s. With dew points in the low to mid 70s, heat indices are expected to reach over 100 degrees to around 105 degrees again in many areas along and west of Interstate 65. This is keeping the Heat Advisory in place through the evening hours. An isolated shower or thunderstorm remains possible, but as with the last couple of days, most areas will remain sunny and dry.

Tonight, winds calm under mostly clear skies early in the night, but as the cold front to the north begins to drop south, clouds are expected to begin increasing across southern Indiana closer to Friday morning. Still a little radiative cooling is expected to help temperatures drop into the upper 60s in some rural areas. The urban areas will remain a little warmer in the low to mid 70s.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 430 AM EDT Thu Sep 17 2026

Heading into Friday, the upper high slides west towards Texas as its negatively tilted upper ridge rotates east through the northern Plains. Northwest flow, ahead of the ridge, will push a surface high through eastern Canada as a the cold front south of the high drops south interacting with shortwaves riding around the upper high, near the CWA. This is expected to increase shower and thunderstorm chances that are expected to work their way south through the CWA. Not expecting much in the way of total rainfall, but additional cloud cover and a shift to northerly winds could help bring relief from warm temperatures. The timing looks delayed, so at least parts of the Heat Advisory may need to be extended into Friday.

Saturday, the front is expected to begin moving back north as a warm front. WAA will keep high temperatures in the low to mid 90s through the beginning of next week before widespread 80s return. The overall pattern remains a little messy with a general zonal flow over the Lower Ohio Valley. A surface low/frontal system is expected to bring increased shower and thunderstorms chances for the beginning and middle parts of next week. Overall rainfall amounts remain low.

AVIATION /06Z TAFS THROUGH 12Z FRIDAY/

Issued at 126 AM EDT Thu Sep 17 2026

High pressure is keeping VFR conditions in place through the forecast period. Winds remain light but will veer towards the northwest throughout the day.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for KYZ023>034-038-045-046-053-054-061>065-070>077-081. IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for INZ076>079-083-084-089>092.