The idiom under the weather does not describe rain, snow, or any other real weather. Literally, under means below something, and the weather means the weather outside. Put together, the words do not make a real physical picture in modern English. The idiom means feeling sick or not quite well. Someone might have a headache, a cold, an upset stomach, or just low energy. If a coworker says, “I’m under the weather today,” they mean they do not feel healthy enough to act completely normal.

Informal everyday health talk

Usage	Explanation	Example
Friendly conversation	Use it when you want to say someone feels a little sick in a casual and gentle way.	I am under the weather today, so I am staying home.
Explaining a bad day	Use it when you need a simple reason for not feeling your best.	She seems under the weather this morning.
Making plans	Use it when you want to cancel or delay plans because you do not feel well.	I cannot come to dinner because I am under the weather.
Talking about work	Use it when you need a polite way to explain lower energy at work.	He said he was under the weather and left early.
Talking about school	Use it when you want to explain that a student is not feeling well enough for class.	My daughter is under the weather, so she stayed home from school.
Small symptoms	Use it when the illness feels mild and you do not want to sound dramatic.	I am a bit under the weather, but I will be fine.

Under the weather is informal and friendly. People use it in everyday conversation with family, friends, classmates, and coworkers. It fits situations like calling in sick, explaining why you missed a meeting, or saying you need to cancel dinner. It sounds natural in speech and in casual writing. You would not use it in a very formal medical report. A person might say, “I can’t come to work. I’m a little under the weather,” or, “She stayed home because she was under the weather.”

The idiom often follows the verb be or feel. Common patterns are be + under the weather and feel + under the weather. Time words often come before or after it to show when the problem is happening. You can say, “I’m under the weather today,” “I felt under the weather this morning,” or “He’s been under the weather all week.” These details work like normal time expressions in English, so the idiom fits into the sentence the same way as other descriptions of health. In conversation, people also shorten the explanation: “I’m under the weather, so I’m going home early.”

Word stress in under the weather

Word	Notation	Description	Example
under	ˈʌn dər	Stress the first syllable and keep the second syllable very light.	Say under clearly at the start of the phrase.
weather	ˈweð ər	Stress the first syllable and let the second syllable fall softly.	Say weather with a strong first syllable.
under the weather	ˈʌn dər ðə ˈweð ər	The phrase sounds natural when you stress UNDER and WEATHER and say the middle words lightly.	She sounds under the weather today.

Say the phrase with two main stresses: UNDER the WEAther. The first word is stronger, and the first part of weather gets the stress naturally. Keep the phrase smooth and connected in normal speech: under the weather. The th in weather is voiced, like the sound at the end of brother. A natural sentence sounds like: “I’m UNDER the WEAther today.”

Several expressions are close to under the weather, but they are not identical. Not feeling well is the most direct and neutral way to say you are sick or uncomfortable. I’m run-down means you are tired, weak, or less energetic, often because of stress, lack of sleep, or too much work. I’ve got a cold is specific and tells the other person what illness you have. Sick as a dog is stronger and more dramatic. It suggests being very ill, and it sounds more colorful than under the weather. A person who is slightly ill may say, “I’m under the weather,” while someone with a clear illness may say, “I’ve got a cold,” or, “I’m really sick as a dog.”