When there last fall it seemed fairly accurate with offshore s/se wind that you get with high pressure inland and no fronts coming down from the North Atlantic. In upper parts of lagoon it can be more gusty or have weaker zones, wind comes down the valleys like the rivers below. I rode there when there were 2-3X OH waves outside so stayed out of the actual river mouth. A 500yd wide 20ft close out dredged by river current did not look inviting. Mind the tide, parts of lagoon very shallow. You can access lagoon from foz do arelho on north side or possibly save driving by launching from south shore, but wind isn't quite as steady in that side and beach very wide. If you are coming in on the highway from Peniche might as well go to foz but mind the fishers/children/other creatures on that side. We found a friendly atmosphere among the kiters.
Didn't get any good onshore while at that spot so no comment on that.