Function note_weather 

pub fn note_weather(
    dir: &Path,
    date: Date,
    weather: Weather,
    at: i64,
    zone: &TimeZone,
) -> Result<(), String>

The weather said for date at at (Unix seconds): the morning’s when it is the first, or a correction within CORRECTION of it; else a change later in the day, forgotten when it comes back to the morning’s.