To have a feeling or hunch that something is the case; a subjective impression without proof.
明日は雨が降る気がする。
I have a feeling it'll rain tomorrow.
その話は本当ではない気がする。
I have a feeling that story isn't true.
彼は今、何か困っている気がする。
I get the sense he's having some trouble right now.
Used after a verb to indicate feeling like doing (or not doing) something; often appears in the negative (e.g. 'don't feel like').
今日は外に出る気がする。
I feel like going out today.
疲れているから、出かける気がしない。
I'm tired, so I don't feel like going out.
甘いものが食べたい気がする。
I feel like eating something sweet.