textproduct: Indianapolis

KEY MESSAGES

- Hot and humid conditions return Today and Wednesday with highs reaching the 90s

- Thunderstorm chances increase late Today through Wednesday night with localized heavy rainfall

- Shower and storm risks persist through late week along a slow- moving frontal boundary

DISCUSSION (Today through Monday)

Issued at 255 AM EDT Tue Sep 15 2026

Early This Morning through Today...

Much of today will be quiet with upper ridging still the main influence across central Indiana. Warm advection will bring in hot and humid air from the southwest, with highs in the lower and middle 90s common across the area. With dewpoints rising into the upper 60s to lower 70s, afternoon heat indices will be in the upper 90s to near 100 in some locations.

Warm mid levels will help keep convection at bay for most areas. However, some influence from upper energy moving around the ridge as well as from a baroclinic zone to the northwest could generate some convection in portions of the western and northern forecast area late this afternoon. Will have some mainly chance PoPs there.

Given the expected instability from the hot and humid conditions, cannot rule out an isolated severe storm with damaging winds. Locally heavy rain will also be a threat.

Tonight...

The baroclinic zone will sag into the northern forecast area tonight. Increasing 850mb winds, additional upper energy, and potential boundaries from earlier convection will all aid in producing some mainly scattered convection tonight.

Similar conditions to late this afternoon will persist into the evening, keeping the threat for an isolated severe storm around. Diminishing instability should end the threat overnight. High moisture content of the atmosphere will keep a threat for locally heavy rain around as well.

Wednesday...

The upper ridge will get flattened some on Wednesday, making upper flow more zonal. This will keep the baroclinic zone in the area, keeping the threat for showers and thunderstorms around. Uncertainties in where this zone will end up along and in sky cover/rain coverage leads to decent uncertainty in high temperatures. High temperatures could range from the middle 80s to middle 90s from north to south.

Thursday through Saturday...

The upper ridge will gradually shift southwest. At the surface, a front will meander across the region. These will keep the threat for showers and thunderstorms around at times, but timing of the highest PoPs remains uncertain. For now will keep PoPs in the chance category or lower.

Depending on where the front is, high temperatures will vary across the area from the lower 80s to the lower 90s, with the potential for middle to upper 90s in the far southwest depending on how far southwest the ridge gets.

Sunday and beyond...

The surface front will gradually move south of the area. This will allow cooler air to gradually filter in. Scattered convection will accompany the front, with chances lowering as the front exits. Highs will cool into the 70s for Monday with lows in the 50s.

AVIATION (06Z TAF Issuance)

Issued at 118 AM EDT Tue Sep 15 2026

Impacts:

- Convection possible late afternoon near KLAF and at most sites tonight Discussion: Outside of convection, VFR conditions are expected through 06Z Wednesday.

There will be some high clouds at times today, along with scattered cumulus developing. This evening, some mid cloud will increase. Convection may develop around KLAF late this afternoon, with some scattered convection potentially developing south and east from there tonight.

Confidence is low in convective development and evolution.

Southeast winds will veer to southwest by this afternoon.

IND WATCHES/WARNINGS/ADVISORIES

None.