Quoting from the midrash, Rashi (possuk 5 of chapter 7) notes that Noach only entered the Teva when the rains began pouring down. That is proof that Noach himself was somewhat skeptical about the flood and only when he actually saw it, did he enter the Teva.
However, there is a problem with this. Didn’t Rashi himself say according to one opinion that Noach was a tzaddik of the highest caliber? Furthermore, even if we would follow the second opinion that he was a tzaddik in comparison to the people of his generation, but not in comparison with other generations; never the less for what reason does the Torah have to publicize this ‘shortcoming’ of his, when in this very Parsha the Torah teaches us not to speak negatively even about animals that are not pure. So we won’t say an impure animal, but wee will say Noach had a deficiency?!
I heard by a farbrengen the following:
As is known, when the Frierdiker Rebbe opened up his Yeshiva in Poland, almost all of the students were from chassidishe families that were not connected to Lubavitch. The Rebbeiim of those communities were warning of the danger that might befall if there was going to be a war. However, the Frierdiker Rebbe was saying there will not be a war.
One of these tzaddikim said to his former chossid, Rabbi Greenglass, “Do you think that your Rebbe doesn’t know there is going to be a war. He definitely knows so.
So you will ask me why is he saying emphatically that there will be no war? The explanation is simple. He is the Tzaddik of our generation, and nothing can happen without his agreement. So he is saying loud and clear that he isn’t maskim (he can’t agree to this). This way the aibishter has to take away some of the harshness of the terrible decree.”
So perhaps this is the explanation by Noach also, he was a great tzaddik and he was demonstrating that he is unhappy with the decree, and therefore was not seeking a haven of safety for himself. This way, he was trying to stop the flood from actually happening.
Alternatively, one has to be careful not to have doubts.
The Frierdiker Rebbe once blessed someone that his relative will come out of Russia. The person was so shocked as to him it seemed as an impossibility that he made a face that expressed his uncertainty, as if he was saying SURE sarcastically.
The reaction was not lost on the Frierdiker Rebbe and he said, “Being that by you it is in doubt, so now by me it is also in doubt.”
This is similar to the famous statement of the Berdichever who admonished a chossid and said, stop thinking like that, those thoughts can erode the power of a brocha.
The Rebbe gave us brochos and said various things, we dare not let the passing of so many years, to cause us doubts, rather we must be firm in our emunah and tracht gut uhn es veit zein gut..