What it means
そうに and そうな express an appearance or impression based on visible signs or a current situation. そうに is used before a verb or another phrase to describe how an action is performed, while そうな is used before a noun to describe something that appears to have a certain quality or to be about to happen. With verbs, attach them to the masu-stem; with i-adjectives, remove the final い; and with na-adjectives, use the adjective stem directly.
Usage note
Do not attach そうな directly to an ordinary noun. For a noun-based prediction, use a verb phrase such as 降りそうな空. The i-adjective いい changes to よさそう, not いそう.
How to use it
彼は元気そうな学生です。
He is a student who looks healthy.
おいしそうなケーキです。
It is a cake that looks delicious.
雨が降りそうな空です。
The sky looks as if it is going to rain.
その犬は元気そうに庭を走っています。
That dog is running around the yard looking healthy.
このりんごはおいしそうに見えます。
This apple looks delicious.
雨が降りそうに見えます。
It looks as if it is going to rain.
彼は元気そうな学生だ。
He is a student who looks healthy.
おいしそうなケーキだ。
It is a cake that looks delicious.
雨が降りそうな空だ。
The sky looks as if it is going to rain.
その犬は元気そうに庭を走っている。
That dog is running around the yard looking healthy.
このりんごはおいしそうに見える。
This apple looks delicious.
雨が降りそうに見える。
It looks as if it is going to rain.