Austin rain chances will increase Wednesday, September 30, as a slow-moving storm system raises the Central Texas flood risk. Heavy downpours may continue into Friday morning before a Pacific cold front ushers in cooler, more fall-like weather.

Austin and Central Texas are preparing for a significant weather change as increasing rain chances, potentially heavy downpours and a growing flash-flood threat replace the late-September heat.

Austin rain chances increase Wednesday

Rain chances are expected to increase Wednesday, September 30, with more widespread showers and thunderstorms developing into the night.

The National Weather Service Austin/San Antonio says the greatest potential for widespread rainfall and flash flooding extends from Wednesday night through Friday morning as a slow-moving weather system crosses the region.

A Pacific cold front, an upper-level storm system and deep moisture are expected to support repeated rounds of rainfall. The Weather Prediction Center also says moisture associated with Polo's remnants will contribute to unusually moist conditions across parts of the Southern Plains.

Central Texas flood risk strengthens

The flood threat is expected to become more significant as the system moves across Texas. The Weather Prediction Center has identified a Moderate Risk of excessive rainfall across portions of the Southern Plains during the period.

Repeated heavy downpours could cause water to rise quickly in flood-prone locations, including low-water crossings, creeks, drainage areas and low-lying roads.

Forecast rainfall totals could reach 2 to 4 inches across parts of the region, with isolated locations potentially receiving 4 to 6 inches. Portions of the Hill Country west of Austin could be particularly vulnerable if the heaviest rainfall repeatedly moves across the same areas.

Cold front brings cooler temperatures

The Pacific cold front helping organize the storms is also expected to bring a noticeable temperature change.

Austin and surrounding areas will remain hot and increasingly humid ahead of the system. After the front moves through Thursday, October 1, temperatures are forecast to fall, with cooler conditions continuing Friday and into the weekend.

Residents across Central Texas should monitor updated National Weather Service forecasts and any watches or warnings because the location and timing of the heaviest rainfall may change as the system approaches.