textproduct: Louisville

KEY MESSAGES

* Highs in the low to mid 90s continue Tuesday as heat builds this week. Chances for heat indices above 100 degrees are highest within the Heat Advisory Tuesday, being near a 60-90% chance of occurring.

* Major Heat Risk is expected from Tuesday through at least Thursday. Depending on possible lack of storms, Friday may be included in this as well.

* A deepening trough will try to push chances for storms into our area Friday evening and Sunday as well.

SHORT TERM /THROUGH TONIGHT/

Issued at 312 PM EDT Mon Aug 31 2026

===== This Afternoon - Tuesday Night =====

A scattered field of cumulus clouds are drifting towards the northeast along a SW flow this afternoon. A very isolated shower is possible across the eastern CWA, but otherwise, everyone remains dry with hot afternoon temperatures in the upper 80s to low 90s. Heat indices have just about maxxed out into the mid 90s and low 100s. Possibly due to the increased dew points, highs have struggled to warm above 90 in a lot of places, acting as a saving grace from heat advisory level heat. Later tonight, skies will clear with lows cooling into the low to mid 70s.

Despite some isolated valley fog (~10%), everyone begins Tuesday warm and calm. With a high pressure continuing its stagnation over the Ohio, our air mass overhead will slowly become drier with residence time. Highs on Tuesday will be slightly warmer than today, reaching the mid to upper 90s in the afternoon. Forecasted heat indices with dewpoints remaining near 70 will reach the upper 90s and low to mid 100s. Because of this, and knowing the synoptic setup encourages hot temperatures at least through Thursday, a Heat Advisory has been issued for tomorrow, Wednesday, and Thursday for heat indices as high as 106 degrees.

Take time to stay hydrated, taking frequent breaks should you be outdoors for prolonged periods of time. Check on your neighbor as well, especially if their A/C doesn't work well or if they have none. SCT cumulus will return, but skies should remain dry still. Lows on Tuesday will be very warm, and may break record warm lows, or at least get close.

LONG TERM /TUESDAY THROUGH MONDAY/

Issued at 312 PM EDT Mon Aug 31 2026

===== Wednesday - Sunday =====

Heat only continues to build Wednesday and Thursday in the stagnant pattern with a high overhead. WSW flow remains with scattered cumulus clouds both afternoons. Temperatures won't vary nor the heat index on either day, with temperatures in the upper 90s with indices in the 100s. In fact, the odds of having heat indices exceed 100 degrees reaches 60-80% in our western communities that gradually decreased below 40% as one approaches the I-75 corridor by HREF guidance. As a result, the Heat Advisory will remain in place for these dates and will be monitored should it need to be extended on Friday. Overnight lows until then will continue to be warm in the mid 70s as well.

By Friday, at least higher above our heads, NW flow will dominate as a trough deepens over eastern Canada. With this NW flow, moisture riding along the NW-SE jet may move into our area. Chances for Heat Advisory level criteria being met is still around 40-60% in our SW CWA but only near 20% in most other areas. This is dependent on the timing of potential storms Friday afternoon/evening. This rain chance is heavily dependent on a weak signal of forcing for ascent, probably form MCSs moving in from the Great Lakes. Without a clear synoptic scale source of support, there is still a great deal of uncertainty on the strength of any storms that may move in from the north and also their timing. For now, highs remain warm in the low to mid 90s with 20-30% of a storm.

===== The Weekend =====

As for the rest of the week and heading into Sunday, the deepening trough over Canada will not move much, allowing for slightly cooler air from the north to filter in with highs in the upper 80s and low 90s by Sunday. Depending on little wiggles on the backside of the trough this weekend, more rain may return on Sunday, although this depends on the positioning of the trough to our east. If it remains too far away, we'll remain dry and allow us to warm up faster for early next week. PoPs will remain low as a result for Sunday.

AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 132 PM EDT Mon Aug 31 2026

VFR conditions are expected throughout the entire TAF period. WSW winds will continue to gust up to 15-20 kts at SDF this afternoon, and occasionally at LEX, though winds will generally begin to calm into the evening. SCT cloud cover will dissipate this evening with clear skies overnight and light to calm winds from the SW. Similar conditions are expected tomorrow with a WSW flow returning, occasionally gusting 15-20 kts, at least at SDF with SCT clouds returning in the mid levels. VFR conditions expected tomorrow afternoon.

LMK WATCHES/WARNINGS/ADVISORIES

KY...Heat Advisory from 1 PM EDT /noon CDT/ Tuesday to 8 PM EDT /7 PM CDT/ Thursday for KYZ023>035-038-061-062-070>072. IN...Heat Advisory from 1 PM EDT /noon CDT/ Tuesday to 8 PM EDT /7 PM CDT/ Thursday for INZ076>079-083-084-089>092.