What is the fine-grained topic of the following text: "A mild to moderate cold wave is sweeping over Rangpur, Rajshahi, Khulna, Barisal, Tangail, Faridpur, Madaripur, Gopalganj, Mymensingh, Sreemangal, Comilla, Feni, Sitakunda and Hatiya, and it may continue for a few days," the forecast said. Only return the topic.
Cold wave in various regions of Bangladesh