I'd like to try to clarify something, just in case the English translation is not 100% accurate - does the Portuguese sentence also imply that it is still not raining?
For me it is someone saying that when he is watching the rain =). If it hasn't been raining since Tuesday, one would probably say "não chove desde terça-feira", "não está chovendo desde terça", "não tem chovido desde terça".
Then the English translation has a different connotation, at least to me. I would have said "it hadn't rained since Tuesday" to express the scenario you've described. It may be just my perception though.