textproduct: Indianapolis

KEY MESSAGES

- Cooler and less humid weather expected through Tuesday

- Scattered showers and storms possible Wednesday evening into Thursday

DISCUSSION (Today through Sunday)

Issued at 301 AM EDT Mon Aug 24 2026

Today through Tuesday night...

Patchy fog has developed across central Indiana this morning due to very light winds and mostly clear skies. Current observations show this fog has mostly developed in climatologically favored locations in valleys or near rivers. Look for this to become more common in favored locations through daybreak before then quickly mixing out after sunrise. Mostly quiet weather conditions are expected early this week with surface high pressure across the region. Aloft, upper troughing shifts east into Tuesday while ridging builds in. This should allow for a slight moderation in temperatures, but seasonably cool temperatures will persist given negligible thermal advection. Highs will generally range from the mid 70s to low 80s.

Very light winds and mostly clear skies again tonight into Tuesday morning will promote patchy fog development. Any fog that develops should quickly mix out in typical diurnal fashion. Surface high pressure begins to shift east late Tuesday allowing for surface flow to become more southerly late overnight.

Wednesday through Sunday

A weakening upper level low riding overtop of the western ridge will drop into the upper Midwest early Wednesday before becoming absorbed by a broader long wave trough that will amplify across the eastern half of the country for late week. Low pressure and an associated cold front running in tandem with the upper wave will track across the Ohio Valley Wednesday evening through early Thursday in a progressively weakened condition as stronger forcing aloft is lost. There will be enough moisture and instability along and immediately ahead of the frontal boundary for scattered convection with the front clearing the forecast area during the day Thursday. Isolated convection is possible on Thursday across east-central IN before the front moves out.

A few strong storms cannot be ruled out Wednesday evening into Wednesday night as guidance depicts moderate instability ahead of the approaching front along with slight enhancement of mid-upper level flow from the approaching wave aloft. Confidence remains low due to varying model solutions, but trends will continue to be monitored. These details should become more clear once guidance is better aligned.

High pressure will reestablish in the wake of the frontal passage drifting slowly east through the Great Lakes into Saturday. This bring another multi day stretch of dry weather with seasonable temperatures as highs will focus largely in the low to mid 80s. The ridge will flatten to the west over the weekend opening the possibility for convection to impact the region by late weekend into early next week as multiple waves ride along in the predominantly zonal flow aloft. Temperatures will also rise back into the mid and upper 80s by the end of the forecast period with an uptick in humidity levels.

AVIATION (06Z TAF Issuance)

Issued at 128 AM EDT Mon Aug 24 2026

Impacts:

- MVFR or worse visibilities in fog possible at outlying terminals 07Z-13Z, especially at KLAF

Discussion:

Mainly VFR conditions to continue across central Indiana through the period as Canadian surface high pressure crosses the Midwest. Expect light and variable winds through daybreak with fog/BR possible at the outlying sites between 07Z-13Z today. Expect northwest winds sustained up to 3-8KT later today before winds become light and variable again tonight. Fog will be possible again at the outlying TAF sites late tonight into Tuesday morning.

IND WATCHES/WARNINGS/ADVISORIES

None.