textproduct: Indianapolis

KEY MESSAGES

- Dry yet pleasant fall weather continues through early next week seasonably cool early mornings, above normal afternoon highs.

- Patchy fog will occur in low lying areas late night/early mornings through Sunday morning.

- A wetter pattern may take shape late next week/Halloween weekend.

DISCUSSION (This evening through Thursday)

Issued at 248 PM EDT Thu Oct 22 2026

Tonight through Sunday...

A broad area of surface high pressure remains centered over Ontario Canada. A surface ridge axis extends southward into the Gulf shunting deep moisture well south of central Indiana. Meanwhile, widespread sinking motion on the eastern edge of upper ridging over the plains will continue to support mostly clear skies. Reinforcements to the ridge of surface high pressure will occur as additional shortwave energy dives southward into the eastern seaboard through Sunday. As a result several more days of very quiescent weather is expected for central Indiana, with highs in the low to mid 70s and light winds. Clear skies, a dry airmass and fairly long nights will continue the stretch of large diurnal temp swings with lows in the low-mid 40s. More late night/early morning patchy fog is also expected in low-lying and traditionally colder spots thanks to ideal radiational cooling conditions.

Monday through Wednesday...

Upper ridging will breakdown over the MS valley as shortwave energy from the western CONUS trough moves eastward into the plains on Monday. Despite increasing high cloud cover, guidance may be underdoing high temps on Monday, given max thickness values in the mid 560s. Although some increasing ascent will occur as the deamplifying shortwave trough approaches the MS valley and central Indiana on Tue/Wed, only an increase in mid level clouds is expected. The surface ridge axis will remain well entrenched over the Gulf, effectively cutting off any moisture return despite southerly BL flow developing. The biggest change to the weather besides the increase in cloud cover will be increase in overnight lows to upper 40s/low 50s Tuesday and Wednesday mornings.

Thursday and Beyond...

Medium range models are in less agreement with the extended period with main differences centered on phasing between shortwave energy moving southeastward through Canada and an upper low/trough over the PAC NW moving eastward towards the northern plains. As a result, the timing of precip is in question. In line with the GFS/GEFS members, the NBM has negligible PoPs through Friday but then opens up the gates for the weekend. While the Op Euro/Euro- AIFS and the GFS-AI have a frontal boundary generating precip across the area on Thursday. Beyond the forecast time period uncertainty grows but there is an increasing composite signal for wetter than normal weather beginning around Halloween into early November.

AVIATION (18Z TAF Issuance)

Issued at 1226 PM EDT Thu Oct 22 2026

Impacts:

- IFR visibility in patchy fog outside of KIND early Fri morning

Discussion:

Another perfect flying day across central Indiana with light winds of 5 kts of less, generally from the NE, and clear skies. High pressure remains the dominant feature both at the surface and aloft.

With clear skies and light winds, another night of patchy fog is expected. Given occurrences of IFR conditions this morning, see no reason to deviate for a similar occurrence to happen at KBMG, KHUF and KLAF Friday morning before 12Z.

IND WATCHES/WARNINGS/ADVISORIES

None.