News reports, weather forecasts, even if the main sentence uses past tense clauses, are they still simple present tense?

This English sentence contains both grammatical errors and useful words that do not conform to English idioms. The correct statement should be:

The weather forecast said it rained yesterday.

In news reports and weather forecasts, the subject uses the past tense, and the tense of the clause depends on the content of the clause, which can be the simple present tense or the simple past tense. The example you gave clearly illustrates "yesterday", and that clause should be the simple past tense.