Alertar Examples, Sentences & Quiz in Spanish

alertar means “to alert” in English, and this page shows you how it actually sounds in everyday Spanish — not just the conjugation table, but the verb in real sentences, in short dialogues, and in the mistakes learners make with it. Alertar means to alert, to warn someone about a danger so they can act in time. It is used for weather, health, security and emergencies, and it is fully regular. Below you will find twelve example sentences grouped by tense, two short dialogues, the most common mistakes with corrections, and a ten-question quiz with explained answers. If you want the full tables first, start with the full conjugation of alertar; if you want to study one tense in depth, see the alertar present tense page.

alertar in everyday use: examples with translations

In the present tense

  1. Yo alerto a la población del peligro. — “I alert the population of the danger.”
  2. Él alerta a los vecinos del incendio. — “He alerts the neighbours about the fire.”
  3. Nosotros alertamos a la policía del robo. — “We alert the police about the robbery.”
  4. Ellos alertan sobre la tormenta que viene. — “They alert about the coming storm.”

In the past

  1. Ayer, yo alerté a los vecinos del incendio. — “Yesterday, I alerted the neighbours about the fire.”
  2. Antes, nosotros alertábamos a la policía del robo. — “Before, we used to alert the police about the robbery.”
  3. Él alertó sobre la tormenta que viene. — “He alerted about the coming storm.”
  4. Yo ya había alertado a la población del peligro antes de salir. — “I had already alerted the population of the danger before leaving.”

Plans, hopes and possibilities

  1. Mañana, tú alertarás a la población del peligro. — “Tomorrow, you will alert the population of the danger.”
  2. Yo alertaría a los vecinos del incendio si tuviera más tiempo. — “I would alert the neighbours about the fire if I had more time.”
  3. Él ha alertado a la policía del robo. — “He has alerted the police about the robbery.”
  4. Espero que él alerte sobre la tormenta que viene. — “I hope he alerts about the coming storm.”

alertar in conversation

Two short dialogues that use alertar the way people really speak it. Notice how the verb changes with the person, and how the same verb fits different situations.

Two friends talk about their day.

  • Ana: Yo alerto a la población del peligro. — “I alert the population of the danger.”
  • Bea: Él alerta a los vecinos del incendio. — “He alerts the neighbours about the fire.”
  • Ana: Ayer, yo alerté a los vecinos del incendio. — “Yesterday, I alerted the neighbours about the fire.”
  • Bea: Mañana, tú alertarás a la población del peligro. — “Tomorrow, you will alert the population of the danger.”

At home, talking about tomorrow.

  • Luis: Nosotros alertamos a la policía del robo. — “We alert the police about the robbery.”
  • Marta: Antes, nosotros alertábamos a la policía del robo. — “Before, we used to alert the police about the robbery.”
  • Luis: Yo alertaría a los vecinos del incendio si tuviera más tiempo. — “I would alert the neighbours about the fire if I had more time.”
  • Marta: Espero que él alerte sobre la tormenta que viene. — “I hope he alerts about the coming storm.”

A short scene with alertar

A short scene shows how alertar works across the day. In the morning: Alerto a la población del peligro. In the afternoon: Alerta a los vecinos del incendio. Yesterday it was different: Ayer, alerté a la policía del robo. And tomorrow: Mañana, alertaré sobre la tormenta que viene. Four small moments, four tenses, one verb — that is how alertar sounds in real life. Try changing the person in each sentence: say it about yourself, about a friend, and about your family, and the forms will start to feel automatic.

Common mistakes with alertar

The errors learners actually make with alertar, each with the wrong form, the right form, and why the right form is right.

✗ Yo alerta a la población del peligro.

✓ Correct: Yo alerto a la población del peligro.

The person matters: alerta is the él/ella/Ud. form, while the yo form is alerto. Using the third-person form with yo is one of the most common beginner errors.

✗ Ayer yo alerto a los vecinos del incendio.

✓ Correct: Ayer yo alerté a los vecinos del incendio.

The present and the preterite are different tenses: alerto is happening now, while alerté is a finished action in the past. Use the preterite with ayer.

✗ Treating alertar and avisar as identical in every context.

✓ Correct: Alertar means to alert, while avisar means to warn or notify.

They overlap, but each has uses the other does not: alertar fits sentences such as Alerto a la población del peligro, while avisar belongs in a different sentence. Check the meaning you want before choosing.

✗ Yo soy alertado a los vecinos del incendio.

✓ Correct: Yo he alertado a los vecinos del incendio.

Spanish perfect tenses use haber, not ser: he alertado, has alertado, ha alertado. Ser plus the participle makes a passive, not a perfect tense.

✗ De niño, yo alerté a la policía del robo todos los días.

✓ Correct: De niño, yo alertaba a la policía del robo todos los días.

For a repeated habit in the past, use the imperfect (alertaba), not the preterite. The preterite (alerté) is for one finished action.

Quiz: alertar in use

Ten questions on alertar — its forms, its tenses and its everyday use. Choose the best answer for each one, then check the answer key below, where every answer is explained.

1. Complete the sentence: Él ______ a los vecinos del incendio. — “He/she alerts the neighbours about the fire.”

  • a) alerta
  • b) alerto
  • c) alertas
  • d) alertamos

2. Complete the sentence: Ayer, yo ______ a la policía del robo. — “Yesterday, I alerted the police about the robbery.”

  • a) alertaste
  • b) alertó
  • c) alertaron
  • d) alerté

3. Complete the sentence: Ellos ______ sobre la tormenta que viene cuando eran jóvenes. — “They used to alert about the coming storm when they were young.”

  • a) alertabas
  • b) alertábamos
  • c) alertaban
  • d) alertaba

4. Complete the sentence: Mañana, nosotros ______ a la población del peligro. — “Tomorrow, we will alert the population of the danger.”

  • a) alertarán
  • b) alertaremos
  • c) alertaré
  • d) alertarás

5. Complete the sentence: Él ______ a los vecinos del incendio si pudiera. — “He would alert the neighbours about the fire if he could.”

  • a) alertaría
  • b) alertarías
  • c) alertaríamos
  • d) alerto

6. Complete the sentence: Yo ______ a la policía del robo. — “I have alerted the police about the robbery.”

  • a) has alertado
  • b) ha alertado
  • c) han alertado
  • d) he alertado

7. Complete the sentence: Espero que tú ______ sobre la tormenta que viene. — “I hope you alert about the coming storm.”

  • a) alertemos
  • b) alerto
  • c) alertes
  • d) alerte

8. Which is the past participle of alertar, used with haber in the perfect tenses?

  • a) alerté
  • b) alertado
  • c) alertando
  • d) alerto

9. What does alertar mean in English?

  • a) to alert
  • b) to warn or notify
  • c) to lodge, to house
  • d) to alter, to disturb

10. Which sentence is correct?

  • a) Él alerta a los vecinos del incendio.
  • b) Él alerto a los vecinos del incendio.
  • c) Nosotros alerta a la policía del robo.
  • d) Yo alerta a la población del peligro.

Answer key

  1. a) alerta — The sentence needs the él/ella/Ud. form in the present: alerta.

  2. d) alerté — The sentence needs the yo form in the preterite: alerté, for one finished action yesterday.

  3. c) alertaban — The sentence needs the ellos/ellas form in the imperfect: alertaban, for a repeated past habit.

  4. b) alertaremos — The sentence needs the nosotros form in the future: alertaremos.

  5. a) alertaría — The sentence needs the él/ella/Ud. form in the conditional: alertaría.

  6. d) he alertado — The sentence needs the yo form in the present perfect: he alertado, haber + alertado.

  7. c) alertes — After espero que, the subjunctive is required: the tú present subjunctive is alertes.

  8. b) alertado — The past participle is alertado: he alertado, has alertado, ha alertado. The gerund alertando is used with estar instead.

  9. a) to alert — alertar means to alert. The other options are the meanings of different verbs.

  10. a) Él alerta a los vecinos del incendio. — Él alerta a los vecinos del incendio. is correct: the verb agrees with its subject. The other sentences mix up the person and the form.

Frequently asked questions

How do I use alertar in everyday conversation?

Start with the phrases in the examples above — especially the common combinations such as Alerto a la población del peligro and Alerta a los vecinos del incendio. Use the present tense for habits and general facts, and the preterite for things that happened once. Say the sentences aloud until the forms feel automatic, then swap in your own details: your own town, your own family, your own routine.

What is the difference between alertar and avisar?

Alertar means “to alert”, while avisar means “to warn or notify”. They are related words that learners often meet together, but they are not interchangeable — use alertar when you mean “to alert” and avisar when you mean “to warn or notify”.

Which tense do I need most with alertar?

The present tense, for habits, routines and general facts — that is where you will use alertar most. The preterite comes next, for things that happened once and ended. The examples on this page use both, plus the imperfect, the future and the present perfect, so you can see the verb across the tenses you actually need.

Is alertar formal or informal?

Alertar is neutral — it is used in both formal and informal Spanish, at home, at work and at school. There is no special formal version of it; the same forms work in a conversation with a friend and in a letter to a company. What changes is the situation, not the verb.

Related links