请问天有不测风云 这句话用英语怎么说啊？

The weather is extremely unpredictable.

A storm may arise from a clear sky.

天有不测风云,人有旦夕祸福.
Storms gather without warning and back luck befalls men overnight.
或
In nature there are unexpected storms and in life unpredictable vicissitudes.

Something unexpected may happen any time.
金山词霸2005

It is the unforeseen that always happens.

We can't foresee everything. (我的翻译，有些勉强)

A storm may arise from a clear sky--something unexpected may happen any time

sky have no car wind cloud!