London had 120,000 residents in 1523.
A fifth of them – 25,000 people – had fled the city by February 1524.
They weren’t running from war or famine.
In the summer of 1523 a group of fortune tellers warned that on February 1, 1524, the River Thames would swell so high it’d swallow London whole. It was met with widespread belief. People panicked.
Some Londoners took shelter in tents a few miles from the city. Others assumed that wasn’t enough. “In January, droves of workmen might be seen, followed by their wives and children, trudging on foot to the villages within fifteen or twenty miles, to await the catastrophe,” Charles Mackay wrote.
The tide, by all accounts, was normal on February 1st.
More here – Collaborative Fund
PS: the question could be broadened to ask why people listen to forecast at all given that the majority of them are wrong – particularly those given by experts.