League City residents can expect afternoon thunderstorms and heat index values above 100 degrees every day through the weekend.

CW39 meteorologist Idolina Peralez and the National Weather Service's Houston office are forecasting scattered showers and storms across Southeast Texas through at least Sunday, Sept. 13. Rain chances range from 30% to 50% daily, with the heaviest coverage near the coast and south of Interstate 10.

The bigger concern is Sunday, Sept. 13. The Weather Prediction Center has placed parts of the Gulf Coast, including portions of Southeast Texas, under a Marginal Risk (level 1 of 4) for excessive rainfall that day. Deep tropical moisture could fuel storms producing heavy downpours, and localized street flooding is possible in low-lying and poor-drainage areas.

That risk is not abstract for League City. Roughly 3,730 homes sit within the city's 100-year floodplain, according to the city's floodplain management page, which cites FEMA maps effective since Aug. 15, 2019. The city and Harris County Flood Control District operate six flood gauge stations within League City's boundaries.

NWS Houston said on Sept. 4 that ground east of I-45 remained heavily saturated from previous rounds of rainfall. The heaviest downpours could produce 2 to 3 inches of rain per hour, the agency said. NWS Houston warned on Sept. 5 that storms could produce locally heavy rainfall leading to street flooding.

Afternoon highs will stay in the low to mid-90s inland. Combined with humidity, heat index values will range from 100 to 106 degrees. The NWS recommends drinking plenty of water, limiting outdoor activity during peak afternoon heat and checking on older adults, children and pets.

League City Mayor Nick Long described the city's storm preparation protocol in a post on X during a separate heavy-rain event in June. City crews clear ditches, check storm drains and ready pumps ahead of expected storms, Long said at the time.

No tropical development is expected in the Atlantic over the next seven days. The pattern of daily 30% to 40% storm chances is forecast to continue into next week.

Residents can monitor water levels at the city's six flood gauge stations through the Harris County Flood Warning System website.