The free version of the weather widget only provides with the bigger cities. If you need a city that is not listed, you will need to subscribe to the World Weather website and obtain the API number for your city. Once you have obtained an API number, you can select the weather widget and select the Premium option. Input the API key within the same window as well.
https://www.worldweatheronline.com/developer/
If you need help with finding the weather for a specific country you can follow the previous steps for this as well.