textproduct: Indianapolis

KEY MESSAGES

- Patchy fog possible this morning

- Warm and dry through mid week with temperatures well above normal

- Rain chances return late week into the early weekend

- Dry and substantially cooler weather expected next week

FORECAST UPDATE

Issued at 958 AM EDT Tue Sep 29 2026

Look for quiet weather conditions through the afternoon as surface high pressure remains in control across the Ohio Valley region. The forecast remains in great shape with only minor adjustments needed. Have increased the hourly temps by 1 deg F based on recent trends. Also boosted wind gusts this afternoon a few mph with slightly deeper mixing expected.

DISCUSSION (Today through Monday)

Issued at 251 AM EDT Tue Sep 29 2026

Dry and warm weather will remain the rule across central Indiana through mid week, as a surface and upper level ridge gradually push eastward. Our next chances for precipitation will come late this week into the weekend, courtesy of a slow-moving frontal system, after which a substantial change to far more fall-like conditions appears likely.

Clear skies and light winds under the surface high this morning should produce at least some patchy fog across the area, particularly just prior to daybreak. Isolated spots of dense fog will be possible, mainly north. This fog will mix out in typical diurnal fashion after sunrise.

Dry and warm conditions will continue through at least early Thursday as a slow moving upper level low gradually absorbs 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 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. Blend keeps low PoPs in the area into Sunday, though given the latest model data this appears to be far too long, and suspect that we'll see this window shrink as the week wears on.

A rumble of thunder or two cannot be ruled out at times, though for the most part, just showers will be expected, though locally heavy downpours will be at least 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, 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.

AVIATION (12Z TAF Issuance)

Issued at 641 AM EDT Tue Sep 29 2026

Impacts:

- Shallow/patchy fog in the first hour at the outlying sites, otherwise VFR

Discussion:

Shallow and/or patchy fog has developed at the outlying sites at times overnight, and this will mix out in typical diurnal fashion shortly after daybreak, but will carry MIFG early and a TEMPO group for 2-3SM fog w/ SCT002 mentioned for the first hour at all but IND.

Expect winds generally southerly during the day at less than 10KT, becoming more southeasterly or light and variable overnight tonight, with just some FEW-SCT high clouds. Cannot entirely rule out patchy fog again tonight, but uncertainty is far too high for inclusion at this time.

IND WATCHES/WARNINGS/ADVISORIES

None.