Under the weather is the polite, gentle way to say that you are not well. It covers a headache, a cold, a bad night of sleep or the tired feeling at the start of a virus. The phrase is soft on purpose: it says you are unwell without describing symptoms.
People often use it to explain why they are quiet, why they left work early or why they cancelled a plan. It is not a medical term, and a doctor would not write it in a report.
This page explains the meaning, the grammar and the register, with examples from work, family life and travel. The drill at the end has 10 questions with an explanation for every answer.
What it means
In one sentence: To be under the weather means to feel ill or unwell, usually in a mild way, or to feel low on energy because of a cold, a headache or a poor night of sleep.
What the idiom means in everyday English
- It describes a person who is not fully healthy: "I am feeling a bit under the weather today."
- The illness is usually mild. It fits a cold, a headache or tiredness better than a broken leg.
- The phrase is often softened with a bit, a little or slightly: "He is a little under the weather."
- It can also mean low in mood or without energy, even when there is no clear illness.
How the idiom behaves in a sentence
- The usual pattern is be or feel under the weather: "She is under the weather", "I feel under the weather".
- Common verbs before it are be, feel, look and seem: "You look a bit under the weather."
- The phrase does not change for tense: "He was under the weather last week", "She has been under the weather all day".
- Do not add a or the. It is under the weather, never under a weather or under the weathers.
When the idiom does not fit
- Do not use it for serious illness. "He is under the weather" is too light for a hospital stay.
- In formal writing, say unwell, ill or unwell for several days. Keep the idiom for speech and messages.
- It describes a person or an animal, not a machine or a plan. A broken printer is not under the weather.
- The phrase can sound like a polite excuse. Say "I am feeling under the weather" instead of a long list of symptoms when you want to be brief.
Use it or not
Register: Informal to neutral. Under the weather is normal in conversation, in a message to your manager and in friendly emails. It is softer and more private than "I am ill", which makes it useful at work. In formal writing, choose "unwell" or "not feeling well". The idiom is not rude, and it is safe in almost any everyday situation.
Examples
- I am feeling a bit under the weather today, so I will work from home.The phrase explains the absence without giving details.
- She looked under the weather at the meeting, so I asked if she was all right.Look works with the idiom to describe appearance.
- The children have been under the weather all week with a cold.The phrase works with the present perfect for a period.
- He said he was under the weather and left the party early.Said he was shows the reported form does not change.
- I was under the weather yesterday, but I feel much better now.The past and present forms sit together naturally.
- You seem a little under the weather. Do you want some tea?Seem works like look and feel with the idiom.
- After the long flight, we were all under the weather for a day.The idiom can describe tiredness after travel.
Similar idioms
out of sorts
slightly unwell or not in your normal mood.
off colour
looking or feeling a little ill, common in British English.
run down
tired and weak, often after working too hard or being ill.
not feeling yourself
feeling different from usual, often because of illness or stress.
sick as a dog
very ill, much stronger and more informal than under the weather.
Practice drill
Answer all 10 questions. Each answer is marked at once, and the meaning is explained under the question.
I feel a bit ___ today, so I am staying in bed.
Show answer and explanation
Answer: A. under the weather Under the weather means feeling slightly ill, which explains why the speaker is staying in bed.
Which sentence uses under the weather correctly?
Show answer and explanation
Answer: B. She is under the weather and has a bad cold. Under the weather describes a person who is ill or unwell; it cannot describe a car or compare two people.
What does under the weather mean?
Show answer and explanation
Answer: C. feeling slightly ill Under the weather means feeling ill or unwell, usually in a mild way.
You look a little ___ today. Are you all right?
Show answer and explanation
Answer: D. under the weather Under the weather fits here because the speaker is asking about the other person's health.
Which situation fits under the weather best?
Show answer and explanation
Answer: A. a headache and a sore throat A headache and a sore throat are mild health problems, and under the weather means feeling slightly ill.
Choose the sentence with the same meaning: "He was under the weather yesterday."
Show answer and explanation
Answer: B. He was ill yesterday. Under the weather means unwell, so the sentence means he was ill yesterday.
Which is correct?
Show answer and explanation
Answer: C. She has been under the weather all week. The fixed phrase keeps the article the and never changes to a or a plural form: under the weather.
Tom says he is feeling under the weather. What is the polite reply?
Show answer and explanation
Answer: D. I hope you feel better soon. Under the weather means Tom feels ill, so a kind wish for his health is the right response.
Which sentence does NOT use the idiom correctly?
Show answer and explanation
Answer: A. My laptop is under the weather and needs charging. The idiom describes people or animals that feel ill, not machines, so a laptop cannot be under the weather.
A colleague cancels a meeting and says she is under the weather. What does she mean?
Show answer and explanation
Answer: B. She is not feeling well. Under the weather is a polite way to say you are ill or unwell, so that is why she cancelled the meeting.
Questions learners ask
Is under the weather formal or informal?
It is informal to neutral. It is safe in conversation, in a message to a colleague and in a polite email. A medical note or a formal report would use "unwell" or the name of the illness instead.
Does under the weather mean sad?
Usually it means slightly ill or low on energy. It can describe a low mood too, especially when the person has no clear illness, but the main meaning is physical: not fully well.
Why do we say under the weather?
The phrase is first recorded in the 1800s, but the reason for the weather image is not well documented. Sailors were said to be sent below deck, "under the weather", when a storm made them seasick, but no text proves that story, so this page does not treat it as the origin.
More idioms
Hit the books
To hit the books is to begin studying hard, usually before a test or an exam.
Raining cats and dogs
If it is raining cats and dogs, it is raining very heavily indeed.
Call it a day
To call it a day is to stop working on something for now, because you have done enough or because the work can wait.
Browse all the idiom pages or take the free A1 to C2 level test to find your starting point.