Torrential rain, fuelled by the effects of the southern monsoon, is expected through Thursday in Fujian, Guangdong, Jiangxi, Hunan, Hubei, Henan and Guangxi, according to the National Meteorological Centre.
State media on Tuesday warned the storm's northward-bound path across mountainous terrain raises the risk of floods, landslides and other disasters before it weakens further.
Noul intensified rapidly before crossing the coast in Guangdong at the weekend, becoming the strongest typhoon to hit China in 2026, according to state broadcaster CCTV.
The authorities are bracing for overlapping typhoon and flood-season risks, with emergency and housing officials ordering stronger flood-control measures, inspections of critical infrastructure and the pre-deployment of rescue teams and equipment in vulnerable areas.
They also called for safety checks on key industries such as mining, hazardous chemicals and fireworks production.
Typhoons typically affect China from July to September, with August being the most active.
In the northwest and southwest, frequent and heavy precipitation has also put Gansu, Sichuan, and Yunnan on heightened vigilance.
Gansu issued its highest warning for geological disasters late on Monday, flagging landslide and mudslide risks in numerous parts of the province after rocks and boulders rolled off mountain slopes onto roads.
Chinese authorities have been searching for 50 people missing after part of a mountain broke off and collapsed onto buildings in a hillside township developed along a river in Chongqing on July 17.
