A dense enough network of automatic weather stations for monitoring a specific urban area and a high resolution numerical weather prediction model enable an accurate forecast of extreme weather phenomenon at least 48 hours in advance. In case an extreme weather signal is captured, the SAEx-L warning is available and enables automatic transmission to SIM card holders who live or are occasionally located in the risk area. SAEx-L also includes advises for appropriate risk-based actions and also a phone number, ready to respond during the entire extreme weather event and to connect the people under the risk to the rescue teams.