"May is a very early time in the year and the weather is usually bad. You cannot run a fast mile race if there is a strong wind, because it makes your running uneven"

This quote by Roger Bannister is referring to the difficulty of running a fast mile race in May due to the weather condition. He is recommending that the weather condition in May is typically bad, and that a strong wind can make running a fast mile race hard. The wind can make running uneven, as it can press the runner in various instructions, making it challenging to preserve a consistent rate. This can be specifically hard for a runner trying to accomplish a fast time. Therefore, it is important to take the weather condition into consideration when running a fast mile race in May.