A colloquial expression meaning "it seems so" or "that appears to be the case," used when something appears true but isn't certain.
明日は雨が降るらしいよ。——そうみたいだね。
They say it will rain tomorrow. — It seems so, doesn't it?
彼女は今日休むらしい。——そうみたい、連絡がないから。
She seems to be taking the day off today. — It appears so; she hasn't contacted us.
インターネットでは売り切れになってるけど、店頭にはまだあるって。——そうみたいなら行ってみよう。
Online it's sold out, but there's still some in stores. — If that's the case, let's go check.