今晚竟然下雨了! (译成英文)

It should rain tonight!(should在此处不是“应该”的意思,而表一种出乎意料的情况)

it actually rainning today!
楼上说得对。
表达了一些惊讶和对事实的肯定

It's actually rainning today!

It actually rained tonight

it is very rain tonight

unexpectedly, it rains tonight!