textproduct: Indianapolis

KEY MESSAGES

- FROST ADVISORY in effect until 900 AM for patchy to widespread frost across central Indiana

- Dry and quiet weather persists this week...subtle moderation amid overall slightly above normal temperatures

FORECAST UPDATE

Issued at 1032 AM EDT Mon Oct 19 2026

Temperatures are steadily warming under clear skies and calm winds with the influence of high pressure. Updated the temperatures to better match the warming trend this morning but still expecting highs in the upper 60s to low 70s.

While winds will be light, surface flow is generally out of the south which will help promote slight warming and lows tonight are expected to be warmer than last night with lows down to near 40.

DISCUSSION (Today through Sunday)

Issued at 228 AM EDT Mon Oct 19 2026

Today and Tonight...

On the heels of the first freeze of the season for approximately half of central Indiana's zones Sunday morning...patchy to possibly widespread frost will be the rule early today...while no areas drop below 33 degrees. Therefore maintaining Frost Advisory for the entire CWA through 900 AM EDT, although latest trends suggest slightly less organized frost with dwpts so far hanging up in upper 30s to near 40F in several, mainly western/southern counties.

Broad and tranquil surface high pressure will facilitate placid autumnal conditions for the start of the workweek. Shift of ridge axis out of Indiana to the east will promote modest moderation of H850 temperatures that will equate to a 3-5 degree increase in temperatures compared to Sunday. Mainly clear skies into most of the afternoon will yield to some cirrus crossing from west to east, especially north of I-70, due to a couple very weak mid-level waves that will have no chance of getting any precipitation through the very dry column. Recent trend in diminishing winds will continue with light flow the rule for at least the next 24 hours...with overall variable headings possibly focusing out of the SSE later today.

Following locally marginal fire weather conditions Sunday...slight rebound of dewpoints/higher minimum RH values and light winds today will prevent fire conditions. High temperatures this afternoon will range from mainly upper 60s to around 70F along the Wabash Valley and southwest of Monroe County.

Tuesday through Thursday...

Zonal ridge across the eastern two-thirds of the CONUS on Tuesday will build northward over the Plains through the mid-week. Meanwhile broad and amplified surface high pressure aligned along the eastern half of the continent will gradually shift its center from southwestern Quebec back into the Great Lakes by Thursday. This will translate to an unseasonably weak surface gradient over central Indiana under occasional cirrus. Wider diurnal temperature ranges will be generally 25-30 degrees...with any overall trend in readings modest and most likely moderating as the building upper ridge to the west allows T850 values to reach 10 degrees Celsius by Thursday.

Surface ridge axis aligned southwestward into East Texas will block any organized return of Gulf moisture. Column moisture will be limited to precipitable water values of 0.90 inches or less, maintaining generally mostly clear skies and surface dewpoints in the 40s to around 50F.

Friday through Sunday...

Dry and placid Mediterranean-like conditions to continue under stacked high pressure late this week as amplified upper ridge glides slowly from the eastern Plains to the Ohio Valley.

Early winter storm tracking near Hudson Bay later in the weekend should drag the tail of its cold/stationary front across the Midwest by Sunday. However, low confidence in return of any noteworthy moisture ahead of this boundary with stubborn and huge southeastern ridge blocking/displacing any Gulf moisture well W/NW of Indiana... with only scattered mid/high clouds expected. Perhaps more notable will be return of light breezes that will veer from easterly Friday to southwest by the end of the weekend. Surprising quiescence in further temperature trends as potent mid-level vort supporting the Canadian system likely suppresses central US ridge somewhat...with readings most likely maintaining range from 40s to 70-75F.

The normal max/min through the forecast period at Indianapolis is 63/43. Temperatures across central Indiana will range from seasonably cool early mornings to slightly above to above normal afternoons.

AVIATION (12Z TAF Issuance)

Issued at 702 AM EDT Mon Oct 19 2026

Impacts: None expected

Discussion:

VFR conditions are expected to continue near central Indiana terminals into Tuesday morning. Stagnant elongated surface high pressure axis draped across Indiana will maintain mostly clear skies...except when very weak upper-level forcing spilling over modest H500 ridge, brings only FEW/SCT cirrus late today and tonight.

Light and often variable winds will prevail through the TAF period, with perhaps a few hours of southeasterly flow under 7KT this afternoon.

IND WATCHES/WARNINGS/ADVISORIES

None.