HOUSTON — While the barrage of deadly thunderstorms that hit Texas has tapered, many cities remain in danger, and officials have warned about the possibility of more flooding from rain-swollen rivers as the week goes on.

In suburban Houston, the rains have pushed the San Jacinto River above flood stage, and its waters were expected to cover streets in subdivisions along the west fork of the river, possibly stranding people in their homes for days if they don’t leave.

In Wharton, about 60 miles southwest of Houston, the mayor asked residents to voluntarily evacuate about 300 homes on the west side of the city due to the predicted rise of the Colorado River. In the rural Parker County community of Horseshoe Bend, some 40 miles southwest of Fort Worth, officials asked residents of about 250 homes to leave as the Brazos River rose.

By early Thursday, Parker County Emergency Management spokesman Joel Kertok said the Brazos River had almost crested, but officials had no reports of flooded homes and were monitoring the situation.

He said the river, which has a flood level of 21 feet, was at about 23 feet.

Meanwhile, in Central Texas, crews continued searching for nine people feared dead after the swollen Blanco River smashed through Wimberley, a small tourist town between San Antonio and Austin, over the Memorial Day weekend. In Houston, residents whose homes were flooded by torrential rains on Monday and Tuesday also continued their cleanup efforts. The storms and floods in Texas and Oklahoma this week have left at least 21 people dead and about a dozen others missing.

While the Houston area got a respite from rainy weather for most of Wednesday, the heavy rains from earlier in the week were still making their way downstream. By late Wednesday, the San Jacinto was at 52 feet, nearly three feet above its flood stage, said Kim Jackson, a spokeswoman for the Harris County Flood Control District.

“We’re advising residents to take any measures that they deem appropriate for their safety as the river continues to rise,” she said.

Joey Shedd, 23, didn’t plan on evacuating his home in the Moonshine Hill neighborhood located along the San Jacinto. Shedd said his home is safe because it stands on stilts, but he expected his parents’ home next door to flood as it is on the ground.