Areas in the Klang Valley are expected to experience thunderstorms, heavy rain and strong winds until about 1pm today, according to the Malaysian Meteorological Department.
Affected areas include Hulu Selangor, Klang, Kuala Langat and Sepang in Selangor, as well as Putrajaya.
Rain has been reported across the country since last night, with several areas leading towards Kuala Lumpur said to be congested due to the downpour.
Members of the public have also been sharing pictures of Sungai Gombak, the flow of which has been on the rise.
Other areas include districts in the north such as Kulim and Bandar Baharu in Kedah and Penang.
In Pahang, there have also been reports of thunderstorms in flood-prone areas like Raub, Bentong, Temerloh, Maran, Kuantan and Pekan.
Down south in Johor, meanwhile, similar weather has been reported in Kluang, Mersing, Kulai, Kota Tinggi and Johor Bahru.
Environment and Water Minister Tuan Ibrahim Tuan Man in a social media post today urged those in the Klang Valley to take extra care while driving during heavy downpours.
According to the infobanjir.my website, the water levels of several rivers are at alert and warning levels.
The Teluk Penyamun station in Kuala Selangor recorded a warning level of 2.93m compared to the normal level of 1.3m.
The Sungai Labu Station at Salak Tinggi in Sepang meanwhile recorded a warning level of 9m compared to the normal level of 7m, while Sungai Rasa, Pulau Meranti, Sepang and Sungai Klang in Bandar Klang are at danger levels.
Several parts of the Klang Valley were hit by major floods following continuous heavy rain last year, causing estimated losses of RM6 billion.
The areas involved included Sri Muda, Bukit Lanchong, and Hulu Langat.
Several settlements in Bentong, Pahang, were also submerged in floodwater.
This year, several areas in Perak and Johor have already experienced floods during the transition phase of the monsoon season which is expected to continue until mid-November.