textproduct: Indianapolis

KEY MESSAGES

- Warm and mostly dry through Thursday with temperatures well above normal.

- Moderate to occasionally heavy rain expected Thursday night into Friday

- Dry and much cooler weather expected over the weekend into next week; first lows to drop into the 30s possible in portions of central Indiana early next week

FORECAST UPDATE

Issued at 934 AM EDT Wed Sep 30 2026

The forecast remains in good shape with only minor adjustments needed to match observations. Current surface analysis depicts surface high pressure centered near southern portions of the Mid-Atlantic while surface ridging extends back into the Midwest. Meanwhile, satellite imagery depicts extensive mid-high clouds from a subtle shortwave moving through aloft and moisture from the remnants of Hurricane Polo streaming in.

A dry layer remains in the low-levels across central Indiana from surface ridging. This will likely limit any chance for measurable precipitation, but a few sprinkles are possible over northern portions of the area where there is greater mid-upper level moisture. Less cloud cover across southern counties should allow for temperatures to warm into the mid 80s during the afternoon while greater cloud cover towards the north generally keeps temperatures in the upper 70s to low 80s.

DISCUSSION (Today through Tuesday)

Issued at 254 AM EDT Wed Sep 30 2026

Warm weather will remain the rule across central Indiana through Thursday, as upper level ridging remains in place to the south. Our next significant chances for precipitation will come late Thursday into Friday evening, courtesy of a slow-moving frontal system, after which a substantial change to far more fall-like conditions is expected.

A few patches of fog are possible again this morning, but significantly increased high clouds over last night suggest far less coverage and little opportunity for dense fog.

Will carry a mention of isolated sprinkles in the north today, as echoes associated with midlevel moisture, subtle upper level disturbances, and a weak jet max aloft slide just to our north, though significant dry air below about 8-12kft will render measurable precipitation exceedingly unlikely - but a few drops may survive to the ground.

For the most part, dry and warm conditions will continue through at least early Thursday as a slow moving upper level low just west of the Four Corners region continues to absorb the remnants of Hurricane Polo and pushes eastward into the central CONUS. The frontal boundary between this system and another large upper low well to our northeast over the eastern Canadian provinces will be held up both by this slow eastward progression and weakening of the closed upper low, and the influence of the upper ridge over the Gulf Coast, but will eventually sag into the area Thursday night into Friday, which is when rain chances will be highest. Almost without exception, dry weather is expected from late Friday night onward, as the blend adapts to recent model runs depicting strong Canadian high pressure dropping into the CONUS over the weekend into next week, bringing much cooler conditions to the area.

A rumble of thunder or two cannot be ruled out at times mainly Thursday night, though for the most part, just showers will be expected, though locally heavy downpours will be a modest concern given precipitable water values near climatological maximum thanks in part to the presence of tropical moisture from the Polo remnants. Recent drier conditions across central Indiana will help to limit hydrologic concerns, however.

In the wake of the front, the aforementioned two areas of strong Canadian high pressure will drop into the region, bringing substantially cooler air and a return to dry conditions for much of the first full week of October, with max temperatures down as much as 15-20 degrees and min temperatures down a solid 10-15 degrees, a bit below seasonal normals and far more fall-like than conditions experienced through the first third of the Autumn season. The first low temperatures of the season to drop into the 30s will be possible early next week.

AVIATION (12Z TAF Issuance)

Issued at 637 AM EDT Wed Sep 30 2026

Impacts:

- None

Discussion:

BKN-OVC skies are expected much of the period as mid and upper level moisture stream into the area ahead of an approaching frontal system. A few sprinkles cannot be ruled out north, but nothing substantial enough to have an impact is expected.

Winds will begin the day light and somewhat variable, eventually becoming more south/southwesterly around 7-9KT, before backing a bit tonight.

Ceilings will gradually lower through the midlevels today, but remaining well into the VFR range, becoming around 8-12kft tonight.

IND WATCHES/WARNINGS/ADVISORIES

None.