être (to be), avoir (to have) and aller (to go) are irregular verbs in any tense. Here are their endings for the future:

être

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I will be je serai
you will be tu seras
he/she will be il/elle sera
we will be nous serons
you will be vous serez
they will be ils/elles seront

Examples

Je serai de retour à 16h.
I will be back at 4pm.
Vous serez sains et saufs.
You will be safe and sound.

avoir

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I will have j'aurai
you will have tu auras
he/she will have il/elle aura
we will have nous aurons
you will have vous aurez
they will have ils/elles auront

Examples

Tu auras plein d'amis.
You will have lots of friends.
Nous aurons 3 enfants.
We will have 3 children.

aller

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I will go j'irai
you will go tu iras
he/she will go il/elle ira
we will go nous irons
you will go vous irez
they will go ils/elles iront

Examples

L'été prochain, elle ira sur la Côte d'Azur.
Next summer, she will go to the French Riviera.
Ils iront au Stade de France.
They will go to the Stade de France.