The future is uncertain, and we often express this uncertainty in how we talk about the future. The same goes for Spanish!
In this article, I will lay out the ways a Spanish speaker can talk about the future, and the different situations in which you might use each.
On one extreme end of the spectrum, we have things that are absolutely certain, or as close as possible. Well, in this case, just like in English, we use the present tense in Spanish.
La clase empieza a las 7:10. → The class starts at 7:30.
Llego la semana que viene. → I arrive next week.
La lluvia termina en febrero. → The rain ends in February.
Notice how in each of these the action is actually in the future, yet we use the present tense, just like English.
In contrast to English, however, when we are committing to doing something in Spanish, we also use the present tense rather than the future:
Estoy en tu casa a las siete. → She will be at your house at seven.
No se lo decimos a nadie. → We won't tell anyone.
Te doy las llaves. → I will give you the keys.
One thing to take care with is that the interpretation of these can be context dependent. Obviously I know you're not giving me the keys now! It's a promise.
Speaking of making plans to do something, you will often see and hear the ir + a +
Voy a ir a tu casa a las ocho. → I'm going to your house at eight.
Vamos a llamar la oficina mañana. → We are going to call the office tomorrow.
Va a comer a las siete. → He is going to eat at seven.
This is also a casual way to talk about any future activity. Some people consider it informal, so while fine for speech, you probably won't see it in legal documents. ;)
Moving further down the certainty spectrum, what if you have not committed to doing something,
but are still considering it? In this case, pensar or estar pensando
¿Qué piensa hacer él esta fin de semana? → What is he thinking about doing this weekend?
Maria está pensando ir al cine. → Maria is thinking about going to the movie.
Note: When followed by an infinitive, you do not use a de after pensar. When you use pensar to mean "thinking about" an object or thing, you would use pensar de followed by that thing.
By the way, Using No pensar is as decisive as it sounds in English. You are not thinking about doing it at all.
One big gotcha going from English to Spanish is the present proressive tense to talk about plans
in the near future. In general, this is not how you would do it in Spanish, where you would most
likely use the ir + a +
Voy a estudiar todo el día mañana. → I'm studying all day tomorrow.
Now we are finally to the future tense. The simplest situation is just like using it where you might use the English where will:
Iré al cine contigo. → I will go to the movies with you.
¿Me llamarás esta noche? → Will you call me tonight?
Here's where it gets more interesting. Besides just what you think will probably happen, you can use the future tense to make predictions.
Habrá mucha comida en la fiesta. → There will be a lot of food at the party.
Ella será una abogada. → She will be a lawyer.
One that may throw you for a loop, the future tense in question form can mean I wonder:
¿Qué hora será? → I wonder what time it is?
¿Dónde estará ella? → I wonder where she is?
This one can get you out of a translation bind. How do you say must in Spanish? Often you might use the future tense.
Miguel estará preocupado. → Miguel must be worried / I guess Miguel is worried.
Juan ya estará en su casa. → Juan must be home by now.
Many of these are simple, but don't let the new ones trick you. Study a few sample sentences and you should have no trouble remembering these new expressions.