under the weather
US /ˈʌndər ðə ˈwɛðər/
UK /ˈʌndər ðə ˈwɛðər/

1.
feeling slightly ill or unwell
:
•
I'm feeling a bit under the weather today, so I might go home early.
•
She's been under the weather for a few days, so she hasn't come to work.
feeling slightly ill or unwell