textproduct: Indianapolis

KEY MESSAGES

- Warm and humid today

- Hot and humid condition expected for much of the upcoming week with multiple days in the 90s and heat indices over 100 degrees

- Heat Advisory in effect Monday afternoon through Thursday

DISCUSSION (Today through Saturday)

Issued at 316 AM EDT Sun Jun 28 2026

Showers have diminished across the forecast area early this morning...leaving a damp and muggy airmass with a thick blanket of lower stratus. 06Z temperatures were mainly in the lower 70s.

The frontal boundary that has served as a focal point for the storms and heavy rainfall in the Ohio Valley over the last few days will begin a northward trek today in response to broad ridging aloft expanding into the region. The ridge will amplify across much of the eastern part of the country over the next several days with an extended stretch of hot and humid conditions lasting into next weekend. This will be easily the hottest weather of the summer to date with dangerous heat indices becoming a primary concern throughout the forecast period.

While it remains quiet early this morning...anticipate an area of convection developing over the Missouri Valley over the next few hours expanding into the lower Ohio Valley towards daybreak. This is courtesy of a subtle wave drifting down the eastern flank of the approaching ridge. The bulk of the convection will remain southwest of central Indiana but a few storms may briefly sneak into portions of the lower Wabash Valley that are waterlogged from repeated rounds of heavy rain the last few days. Will maintain low pops in the far southwest counties for a few hours around daybreak.

The primary impacts through mid morning will be low stratus and areas of fog developing with the near surface layer saturated and only very light wind flow. As low level mixing develops later this morning will see ceilings begin to lift but considering the moist boundary layer conditions...expect a broken cu field to linger over much of the forecast area all day. Model soundings do show an increasingly unstable airmass developing this afternoon but also a gradual strengthening of a mid level cap as heights aloft rise. Cannot entirely rule out a stray shower or storm as a result but chances look too low for a mention in the forecast at this time especially with no appreciable forcing aloft present.

The upper level ridge will continue its expansion in the area tonight with an extended stretch of days with highs above 90 commencing on Monday. The core of the ridge peaks with heights at 596-597dam by Tuesday and Wednesday before slowly flattening by next weekend. Daily max heat indices above 100 degrees Monday through perhaps as far as next Saturday will warrant a Heat Advisory issuance beginning on Monday. While there are still a few details to work out...the most efficient way to message this upcoming significant heat will be with an extended multi-day Advisory out for much of the upcoming week. The expected length of the upcoming heat wave with several nights with lows in the 70s could lead to adjustments in the headlines as the week progresses.

Isolated late afternoon and evening convection may develop as early as Thursday as the mid level heights begin to slip back in response upper level waves tracking across the northern tier of the country. This will become even more prevalent as the ridge flattens into next weekend with an increasing threat for scattered convection over parts of the forecast area.

AVIATION (12Z TAF Issuance)

Issued at 551 AM EDT Sun Jun 28 2026

Impacts:

- Widespread sub-IFR conditions through mid morning in fog and low stratus

- VFR conditions returning for this afternoon and tonight

- Patchy fog possible at KBMG predawn Monday

Discussion:

Widespread IFR and lower conditions were ongoing at the terminals early this morning due to low stratus and fog. This will persist for the next few hours before low level mixing commences and enables ceilings to lift back to VFR levels early this afternoon. Broken cu will linger through the afternoon with clouds decreasing in coverage tonight as upper level ridging expands into the Ohio Valley.

Winds will remain below 10kt throughout the forecast period and occasionally calm to light and variable this morning. Light southerly flow develops for this afternoon and tonight. Patchy fog may develop predawn Monday at KBMG.

IND WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon Monday to 8 PM EDT Thursday for INZ021- 028>031-035>049-051>057-060>065-067>072.