textproduct: Indianapolis

KEY MESSAGES

- Heat index values between 105 to 110 daily through Friday

- *Extreme Heat Warning* in effect through Friday evening

- Thunderstorm chances will increase Friday through the holiday weekend

FORECAST UPDATE

Issued at 1000 PM EDT Wed Jul 1 2026

Tonight will be a near-carbon copy of yesterday across central Indiana, with July starting amid continued unseasonably warm and very humid overnight conditions as stagnant stacked ridge continues to spin over the southern Appalachians. Mainly clear skies will oversee diminishing light south-southwesterly breezes...which may again allow patchy pre-dawn fog, with visibility falling locally to under 2 miles...especially over southern counties. Dewpoints will again guide nighttime minimums...with lows of 72-74 common across the region by early Thursday.

DISCUSSION (This evening through Wednesday)

Issued at 301 PM EDT Wed Jul 1 2026

Overview.

An intense heat wave will continue across central Indiana through Friday with dangerously hot and humid conditions expected. The Extreme Heat Warning has been extended through 8pm Friday with peak heat index values of 105 to 110 possible each afternoon and little to no relief from the heat overnight. Look for some slight relief this holiday weekend into early next week as storm chances begin to increase.

Today through Friday night...

Guidance continues to depict upper ridging deamplifying through the end of the week allowing for rain chances to eventually return late Friday once subtle impulses begin to approach. While the ridge should break down, the hot and humid airmass is already in place so look for dangerously hot conditions to continue through Friday with little relief overnight. Look for large scale subsidence to keep weather conditions mostly quiet until the ridge flattens out towards the end of the work week allowing for waves aloft to move through. Deep-layer wind shear for storm organization appears weak, but strong destabilization and steep low-level lapse rates could support isolated damaging wind gusts Friday afternoon or evening.

Saturday through early next week...

Long range guidance depicts a few shortwaves moving through aloft during the period. Weakening large scale subsidence and at least modest dynamics from the approaching impulses will provide greater opportunities for convection, particularly over the weekend. Potential for diurnal convection can also be expected with strong daytime heating atop an anomalously moist PBL.

A few severe storms cannot be ruled out given strong destabilization each afternoon. The primary threat would be isolated damaging wind gusts from microbursts in the weakly sheared environment, mainly during the afternoon or evening hours. A few models still suggest the potential for a few MCSs to develop near the region over the weekend. Confidence on this scenario remains low due to a large spread in model solutions, but overall flow could allow for any storm cluster to propagate towards central Indiana. Specific details will remain uncertain until models become better aligned.

Humid conditions will continue through the weekend while temperatures remain hot. Some slight relief from the heat appears possible this weekend into early next week with additional chances for convection. Guidance also suggest a front associated with a more organized shortwave could dive south early next week. ECMWF and GEFS members differ on exact timing, but the boundary will likely reinforce convective chances along with helping to trend temperatures closer to seasonal averages.

AVIATION (00Z TAF Issuance)

Issued at 724 PM EDT Wed Jul 1 2026

Impacts:

Chance of brief MVFR/IFR VIS in patchy fog within 09Z-12Z tonight

Discussion:

Mainly VFR conditions will continue across central Indiana through Thursday evening...with patchy fog late tonight possibly dropping visibility to MVFR/very brief IFR levels at KBMG/KLAF, mainly within 10Z-12Z. Otherwise very warm and humid conditions will continue through the TAF period as the prevailing stacked subtropical ridge continues to spin over the eastern third of the CONUS.

FEW cumulus around 4,000 feet will diminish through the early evening leaving only stray cirrus overnight...ahead of a mostly clear Wednesday AM and another afternoon with FEW/SCT cumulus to end the TAF period. Near carbon-copy of winds, varying slightly from SSW at night to more SW during midday/afternoon hours...with flow falling below 7KT by 04Z...and again mixing up to 7-10KT for Wed afternoon.

IND WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 8 PM EDT Friday for INZ021-028>031- 035>049-051>057-060>065-067>072.