Today is a short but major fact: Many people will frequently write the exclamation “woah.” However, that word’s primary dictionary entry is found alongside other slang in Urban Dictionary.
Instead, the word is properly spelled “whoa,” per Merriam-Webster, dictionary.com, etc.
You’re certainly not alone if you spell it “woah.” But if it’s the first time you’re hearing that it’s an improper spelling, that might make you say, “whoa.”