It is a fair point on climate change. I'm not really an expert on this, but I'll make some various points...

I think winters have become drier, but April can be absolutely torrential.

The specific location can also make a difference. I'm near the base of a mountain which I believe can prop-up the underground water table nicely, and can certainly cause more rain.

I think Portugal being costal also helps with rainfall, certainly compared to the plains of Spain further East.

Try and get some data for the last decade or two. That will probably be more useful than any local anecdotes. But local terrain/micro-climates will make a difference.

How would I be able to check remote if a piece of land will have good or even very good internet?

Is 15000 sqmt for 100k possible?

Are you aware of any community to exchange experience?

Land in this area is roughly €1/m2, although it will be more if it has a house on it or existing amenities.

Regarding internet access, you can use our coverage checker :-) gardunha.net. We only cover a small area of Portugal.

There are some Facebook groups for people who have done similar things, although they do have some odd people in them. Lookup Pure Portugal.

"Is 15000 sqmt for 100k possible?"

Surely it is.

https://www.idealista.pt/en/point/comprar-terrenos/39.62296/...