We use the present continuous, sb + am/is/are + -ing, to talk about the future. It is not the present tense in this case, it is a future form, but the structure of the language is the same. We use it to express arrangements.
When you make a decision at the moment of speaking, you use will. Then you start planning and use going to. After the plans have been made, you have arrangements, and the present continuous expresses these arrangements.
The present continuous is used for a definite arrangement as opposed to a decisión to do something.
a) I am meeting my friend tonight. (this is planned, you know what time and you know where you are meeting)
The future continuous, will + be + -ing, is used to talk about what will be happening at a particular moment in the future.
b) I will be cycling out of Spain and into France at 9am on Saturday morning.
There are times when you could use both, but if you are trying to say that you have an arrangement to do something, and so can’t do something else, you would use the present continuous to show this.
c) I’m having lunch with Mary tomorrow.
It is true that at a particular time in the future, you will be having lunch with Mary, but if you want to show that you have made arrangements to see Mary. You have made bookings, bought travel tickets, or concert tickets etc.
Choose the correct option, or underline both if both are possible.
a) We are flying/we will be flying to China next Wednesday at 9am. Our flight departs at 7am.
b) At this time next week, we’re lying/we’ll be lying on the beach in Mauritius. I can’t wait!
c) My brother and his friend are going hiking/will be going hiking in the jungle tomorrow I’m worried about him – I hope he’ll be ok.
d) The train station is having/will be having major renovation work in June. Prepare to have disruptions on your daily commute.
e) My father is getting married/will be getting married again on Saturday morning. This will be his fifth marriage!
f) I can’t believe at this time next week we’ll be getting married/we are getting
g) We are starting university/will be starting University next Autumn. I can’t believe how time flies.
h) My family will be going on holiday/is going on holiday to London in August.