Current weather shows it's sunny even if it's already nighttime

@hellothere1234 , just like Crin and @x4m1r4 said, this is to show that the weather is clear.   I've seen the same thing on several other games, including The Legend of Zelda: Breath of the Wild!  The symbol for clear is a sun even at night.  I guess the thinking on that is that you don't have two different symbols for rain just because it sometimes rains at night.  You would be using the clock to tell the time anyway, not using the weather forecast to tell the time. 😉