According to IPMA, the bad weather should start by affecting the islands of the central group (Terceira, São Jorge, Pico, Graciosa and Faial) and western (Flores and Corvo).
The IPMA has issued a yellow warning for the central group between 00:00 local time (01:00 in Lisbon) and 12:00 on 9 September, given the forecast of precipitation, which could be followed by thunderstorms.
For the western group, the yellow warning will be active between 00:00 and 09:00 on Friday.
In the eastern group (Sao Miguel and Santa Maria), the yellow warning is in effect between 12:00 and 21:00 on Friday.
Following the weather warning, the Regional Civil Protection and Fire Service of the Azores advises that self-protection measures should be taken for these weather situations.
Among other measures, they suggest the population to keep drainage systems clean. "Stay indoors. You could get in the way of the security forces and put your safety at risk, particularly by falling into holes hidden by water sheets ," they added.
If you have "noticed a situation that could cause damage, please inform the competent authorities", the Regional Civil Protection Service also recommends.