textproduct: Louisville

KEY MESSAGES

* Hot and humid today with afternoon highs in the low to mid 90s. An Extreme Heat Warning remains in effect through Thursday. * A strong ridge of high pressure over the region will bring the hottest temperatures so far this year. The combination of heat and high humidity will yield afternoon and evening heat index values of 105+ through Thursday.

* Hot and humid for the Fourth of July holiday weekend, with isolated to scattered storms possible in the afternoon and evening. Localized flash flooding and/or localized gusty winds will be possible each afternoon and evening with any slow moving storm.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 341 AM EDT Tue Jun 30 2026

Conditions are warm, humid, but dry early this morning. Skies are mostly clear, with just a few cirrus drifting southeast. Temperatures are mostly in the mid to upper 70s, with a few KY Mesonet sites in the lower 70s. Other than some river valley fog, no significant weather is expected through sunrise. Satellite imagery shows more widespread valley fog across eastern KY, and this fog is starting develop further west along the Cumberland, Green, and Kentucky rivers.

A strong upper level ridge will be centered over the Ohio Valley through Wednesday. 500 mb heights remain at or above the climatological 99th percentile during this time. Temperatures appear set to rise at least 2-3 degrees higher than yesterday. Afternoon temperatures will soar into the low to mid 90s, held back only by abundant low-level moisture and elevated soil moisture. Oppressive humidity contributes significantly to the dangerous heat this week, with sfc dewpoints still in the mid and upper 70s. Today, afternoon heat index values are forecast to top out in the 100-105 range in the Bluegrass Region. Elsewhere, peak heat index values of 105-115 are expected. The combination of heat and humidity will significantly increase the risk for heat-related illness.

Temperatures will drop back into the low to mid 70s early Wednesday morning, offering only brief relief through sunrise.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 341 AM EDT Tue Jun 30 2026

Wednesday Night - Friday Night...

Hot and humid conditions will linger through the end of the week, but rain and thunderstorm chances will gradually creep back in beginning Thursday. The center of the mid-level ridge shifts across the central Appalachians on Thursday, and PWATs are forecast to increase to 1.6-1.8 inches on the western periphery of the ridge. While we lack a forcing mechanism, forecast soundings show strong instability and bit less mid-level capping. LREF members increase forecast confidence in at least isolated pulse convection Thursday afternoon and evening. While confidence in storm coverage is low, any storm that is able to develop would be capable of a brief torrential downpour, strong winds, and lightning.

The lack of greater convective coverage likely won't prevent temperatures from reaching the mid 90s Thursday afternoon. The current Excessive Heat Warning reflects the multi-day heat risk well, and no changes are planned at this time. Increasing shower and thunderstorm chances on Friday lower forecast confidence in high temperatures.

The center of the ridge moves over the East Coast for Friday and Friday night, with a fairly active upper flow pattern across the northern CONUS. Will start to need to watch for upstream MCS activity possibly taking aim at our area heading into the weekend. Even without an MCS, isolated to scattered afternoon pulse convection appears likely, which could linger well into the evening. Very slow storm motions, strong instability, and fairly high PWATs will increase the risk for torrential rainfall and localized flash flooding. Stronger storms could also produce localized microbursts.

Saturday - Monday...

For the Fourth of July weekend, expect hot and humid conditions with daily thunderstorm chances. Weakened upper ridging, and the presence of increased convective activity just upstream across the Midwest, will contribute to greater thunderstorm chances over the weekend. More pronounced upper level troughing develops over the Midwest this weekend, especially by Sunday. We'll then see a weak cool front dip in from the northwest heading into Monday. The hot and humid airmass will still support high rainfall rates, leading to at least a low- end threat for isolated flash flooding.

AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 137 AM EDT Tue Jun 30 2026

VFR conditions likely. SCT cirrus are spreading southeast over the region early this morning. Expect very light southerly winds through sunrise. Winds will increase to 5-7 kts out of the southwest during the mid to late morning hours on Tuesday. Expect a SCT cumulus deck after 16Z, with a bit more cu coverage over LEX and RGA.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Extreme Heat Warning until 9 PM EDT /8 PM CDT/ Thursday for KYZ023>043-045>049-053>057-061>067-070>078-081-082. IN...Extreme Heat Warning until 9 PM EDT /8 PM CDT/ Thursday for INZ076>079-083-084-089>092.