If the twenty-fourth of August be fair and clear, Then hope for a prosperous autumn that year.

Pleasant, clear weather on 24 August is treated as a hopeful sign that the coming autumn will be prosperous.

The proverb draws a connection between the weather on one late-summer day and the fortunes of the season ahead. It expresses hope rather than a guarantee.

Use it when commenting on clear weather on 24 August, or when discussing the practice of reading a particular day's weather as a sign of what the next season may bring.