HEADLINES
– Heat increases today, humidity tomorrow into the weekend until Tuesday.
– Heat index values near or exceeding 100 at times likely Saturday through Tuesday.
– Isolated storm possible in the weekend afternoons and Monday.
– Greater threat for storms Tuesday and Wednesday ahead of a (welcome!) cold front.
TODAY’S MAP
NWS TECHNICAL DISCUSSION
Scattered cumulus will pop up during the day, but warming mid-level temperatures should prevent these from growing into showers and storms. However, cannot absolutely rule out a stray shower. Odds for these will be less than 15 percent, so will not mention. Highs will be around 90 today, but it will feel more like the lower and middle 90s thanks to the higher dewpoints. Tonight... Cumulus will dissipate this evening, but some high clouds from convection well to the northwest may move into the area during the night. With the higher dewpoints and light winds expected, patchy ground fog will develop in favored areas. A few CAMs are showing convection riding around the upper high into the area late tonight. However, these develop storms farther south than would be expected given location of forcing. Will side with the majority of CAMs and keep the area dry. Lows will be in the upper 60s and lower 70s. && .LONG TERM (Saturday through Thursday)... Issued at 301 AM EDT Fri Aug 15 2025 Saturday through Monday... The main focus early in the extended will be unseasonably hot and humid conditions. Aloft, ridging remains near the region keeping an anomalously hot airmass in place. Highs in the low-mid 90s combined with high humidity will lead to peak heat indices reaching near 100- 105 degrees each afternoon. Increasing low-level moisture may be enough to promote a few diurnal showers Saturday given strong daytime heating, but potential appears too low to add any rain chances at this time. Guidance suggest there is another slightly higher chance for precipitation Sunday or Monday when upstream storm complexes riding along the ridge propagate towards the area. These storms should weaken as they move into a less favorable environment over Indiana with weaker forcing and deep-layer shear. However, cannot rule out convection persisting into portions of central Indiana. Will keep low POPs primarily over northern counties on Sunday to account for the low potential. POPs were not added for Monday due to diverging model solutions limiting forecast confidence. It is typical for models to struggle with these subtle impulses riding along the northern periphery of ridges. Rain chances will likely need to be refined once guidance becomes better aligned. Any convection or convective cloud debris could limit peak heat indices. Tuesday onward... Upper troughing setting up over the region Tuesday and Wednesday along with a cold front moving through will support better chances for precipitation. Uncertainty in exact details remains due to diverging model solutions though. Expect greater coverage of showers or thunderstorms with the threat for localized heavy rain and gusty winds. Peak heat indices around 100-105 are still possible Tuesday ahead of the cold front before cooler air filters in mid-late week. Highs should generally fall into the 80s again towards late next week with lower humidity. Rain chances will also diminish as a drier airmass moves in.
INDY SEVEN DAY FORECAST
Today: Mostly sunny. Hotter. High 91.
Tonight: Mostly clear. Humidity increases. Low 72.
Saturday: Mostly sunny. Hot and humid. Isolated late afternoon shower or storm possible. High 93.
Saturday Night: Partly cloudy. Isolated shower or storm possible. Low 74.
Sunday: Mostly sunny. Isolated late afternoon shower or storm possible. High 95.
Sunday Night: Partly cloudy. Low 74.
Monday: Partly sunny, with spotty afternoon showers and storms. High 95.
Monday Night: Partly cloudy. Low 74.
Tuesday: Partly to mostly cloudy, with scattered showers and storms. High 92.
Tuesday Night: Scattered showers and storms. Low 72.
Wednesday: Partly to mostly cloudy, with scattered showers and storms mainly in the morning. High 84.
Wednesday Night: Partly cloudy. Not as humid! Low 66.
Thursday: Partly sunny. High 83.
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