In the UK weather stations are on a 40km grid and even with that weather interpretation even by the experts can be incorrect.
Amateurs trying to interpolate weather from two stations about 80km apart is a hiding to nothing.
We have all heard and some experienced the "p*****g with rain on one side of the street and sunny on the other".
Now, yes. It's not always easy to find historical daily records going back 9 years.
I've found two for Sagres and even so, they don't correspond to the precise location - two are 10-12 km away (Sagres) and the other is 40km away in the direction of the advancing bad weather in Faro).
The weather may, of course, be better or worse even a few km away... but taking Faro airport as conditions prevailing in the little cove of PdL 40km to the west as "proof" of anything seems somewhat precarious...
NB: I stil don't understand how this RAF ex-pat didn't notice any activity on the evening of 3 May when he got to his apartment, wherever that was. As I can't find any indication of where he actually was that night, he might not have been in PdL at all