Here are two sentences which, in my opinion, can't be both right.
Said in the morning:
If it rains this afternoon, then yesterday's weather forecast will be wrong.
If it rains this afternoon, then yesterday's weather forecast was wrong.
Sticking to the rules, the first one is correct because we won't know if the forecast is right or wrong before later in the day. (Conditional type 1)
But, following the logic — the second one doesn't seem incorrect because the forecast was already wrong yesterday, but this will be proved later today when we say: Yesterday's forecast was wrong."
My questions are:
Which of the two is grammatically correct, and if it is the first one, why not the second (and vice versa)?
Would it be correct with would in the main clause:
If it rains this afternoon, then yesterday's weather forecast would be wrong.
If it would, what type of conditional would it be then?
Any helpful answer will be highly appreciated.