A bridge over the 405 Freeway connecting Costa Mesa and Irvine will be closed for repairs a few weeks longer than expected because of recent rain, officials said Tuesday.

Red Hill Avenue will remain closed to all traffic between Pullman Street in Costa Mesa and Main Street in Irvine until mid-January. Originally, the road was expected to be blocked off until Dec. 30, but the closure had to be extended “because the construction area experienced water saturation due to the recent rains,” said California Department of Transportation spokeswoman Jocelyn Whitfield.

The stretch of Red Hill was closed Aug. 29 so workers could stabilize the embankment under one of the approach ramps to the bridge.

The city of Costa Mesa posted an online notice Tuesday about the extended closure and cautioned motorists that they “may experience delays and are advised to avoid the area, use alternate routes and check traffic conditions before traveling.”

The closure is necessary because the earth under the approach ramp on the Costa Mesa side is moving, which has caused walls meant to keep the soil in place to bulge and “triggered progressive pavement cracks on the roadway above,” according to Caltrans.

The $9.5-million repair project, which is funded through the State Highway Operation and Protection Program, entails reinforcing the underlying soil and constructing new retaining walls.

For more information about the project, visit dot.ca.gov/dist12/Red_Hill.

luke.money@latimes.com

Twitter: @LukeMMoney