Quando a humidade está alta, eu sinto cansaço.

When the humidity is high, I feel tired.

Breakdown of Quando a humidade está alta, eu sinto cansaço.

• eu: I
• estar: to be
• quando: when
• sentir: to feel
• o cansaço: the tiredness
• alto: high
• a humidade: the humidity

Questions & Answers about Quando a humidade está alta, eu sinto cansaço.

Why is there an article in a humidade, when in English we just say when humidity is high without the?

In European Portuguese, abstract or general things often take the definite article, especially in statements about general conditions or facts.

• a humidade está alta = literally the humidity is high
• But it is used in a general way, so it corresponds to English humidity is high.

So:

• Portuguese: Quando a humidade está alta, eu sinto cansaço.
• Natural English: When humidity is high, I feel tired.

Using a is normal and sounds natural in Portuguese here. Saying Quando humidade está alta (without a) sounds wrong.

Why is it humidade and not umidade?

Both words exist, but they belong to different varieties of Portuguese:

• humidade – European Portuguese (Portugal)
• umidade – Brazilian Portuguese

The sentence you gave is in European Portuguese, so humidade is the correct form there.

Pronunciation tip:

• The h in humidade is silent. It sounds the same as umidade in Brazilian Portuguese.

Why is the verb está (from estar) used, and not é (from ser)?

In Portuguese:

• ser is used for permanent or defining characteristics.
• estar is used for temporary states or conditions.

Humidity being high is seen as a temporary condition (it changes with the weather), so you use estar:

• A humidade está alta. – The humidity is high (now / at this time).

If you said A humidade é alta, it would sound like you are describing a permanent characteristic of that place’s climate, which is less likely in this context.

Why is the verb in the quando clause just present indicative (está) and not the subjunctive, like estiver?

In Portuguese, quando can take either:

• the present indicative for general or habitual facts:

  • Quando a humidade está alta, eu sinto cansaço.
  • = Whenever humidity is high, I feel tired. (general pattern)

• the future subjunctive for specific future situations:

  • Quando a humidade estiver alta, vou sentir cansaço.
  • = When the humidity is high (in the future), I will feel tired.

Your sentence talks about a general, repeated situation, so the present indicative (está) is correct and natural.

Could I say Quando a humidade está alta, sinto cansaço without eu?

Yes, and in European Portuguese this is actually more natural:

• Quando a humidade está alta, sinto cansaço.

Portuguese is a pro‑drop language: the subject pronoun (eu, tu, ele…) can be dropped because the verb ending already shows the person:

• sinto clearly shows 1st person singular (I).

You only keep eu if:

• you want to contrast or emphasize it:
  Quando a humidade está alta, eu sinto cansaço, mas o meu irmão não.
• or for clarity in a more complex context.

But in isolation, dropping eu is perfectly fine.

What is the difference between sinto cansaço, sinto‑me cansado and estou cansado?

All three relate to feeling tired, but they sound slightly different:

1. sinto cansaço

   • Literally I feel tiredness / fatigue.
   • Focuses on the sensation of fatigue as something you feel in your body.
   • Sounds a bit more neutral or descriptive, sometimes a bit formal.

2. sinto‑me cansado / cansada

   • Literally I feel tired.
   • reflexive form: sentir‑se + adjective.
   • More subjective: you are describing your own state.
   • Very common and natural in everyday speech.

3. estou cansado / cansada

   • Literally I am tired.
   • The most direct, everyday way to say you are tired.

In your sentence, you could say:

• Quando a humidade está alta, estou cansado.
• Quando a humidade está alta, sinto‑me cansado.
• Quando a humidade está alta, sinto cansaço.

All are correct; they just have slightly different nuances of style and focus. The original emphasizes the feeling of fatigue as a kind of symptom.

Why is there no article before cansaço? Why not eu sinto o cansaço?

Here cansaço is being used like an uncountable mass noun (fatigue in general), and it’s the direct object of sinto:

• Eu sinto cansaço. – I feel (some) fatigue / I feel tiredness.

No article is needed because we are not talking about a specific, defined instance of fatigue.

If you say:

• Eu sinto o cansaço.

…it sounds like the fatigue is already known or defined in the context, or like a more literary style (e.g. Eu sinto o cansaço do dia inteiro. – I feel the fatigue from the entire day).

Why is the adjective alta and not alto?

In Portuguese, adjectives must agree in gender and number with the noun they describe:

• a humidade – feminine singular
• So the adjective must be feminine singular: alta

Examples:

• a humidade alta – high humidity (feminine singular)
• o calor alto – high heat (masculine singular)
• as temperaturas altas – high temperatures (feminine plural)

So:

• A humidade está alta. ✅
• A humidade está alto. ❌ (wrong agreement)

Is the word order fixed, or can I say Eu sinto cansaço quando a humidade está alta?

Both orders are grammatically correct:

• Quando a humidade está alta, eu sinto cansaço.
• Eu sinto cansaço quando a humidade está alta.

The meaning is the same. The difference is only in emphasis:

• Starting with Quando a humidade está alta highlights the condition (the humidity).
• Starting with Eu sinto cansaço highlights you and your feeling.

In practice, both are natural, and speakers freely alternate between them.

Is there anything special about the comma before eu sinto cansaço?

The comma marks the end of the dependent clause introduced by quando:

• Dependent clause: Quando a humidade está alta
• Main clause: eu sinto cansaço

In European Portuguese, it’s standard to use a comma when a dependent clause comes before the main clause:

• Quando a humidade está alta, eu sinto cansaço.

If you reverse the order, you normally don’t use a comma:

• Eu sinto cansaço quando a humidade está alta.

Could I say Quando a humidade estiver alta, eu vou sentir cansaço instead? How does it change the meaning?

Yes, that’s correct, but the nuance is different:

• Quando a humidade está alta, eu sinto cansaço.
  – General, habitual fact. Whenever humidity is high, this is what happens.

• Quando a humidade estiver alta, eu vou sentir cansaço.
  – Refers to a future situation.
  Literally: When the humidity is high (at some point in the future), I’m going to feel tired.

So:

• Use está (present indicative) for general truths and repeated patterns.
• Use estiver (future subjunctive) when you’re talking specifically about something that will happen in the future.

Could I replace humidade with another word, like calor, and keep the same structure?

Yes. The structure is very flexible. You can swap a humidade for other weather or condition nouns:

• Quando o calor está alto, eu sinto cansaço.
  (When the heat is high, I feel tired.)
• Quando a temperatura está alta, eu sinto cansaço.
• Quando a pressão está baixa, eu sinto cansaço.

Just remember to:

• Use the correct article (o / a) for the noun.

• Make the adjective agree with the noun in gender and number:

  • o calor alto
  • a temperatura alta
  • as temperaturas altas