We use may and might to talk about possible actions or happenings in the future:
I haven’t decided yet where to go on vacation. I may go to Hawaii. (= perhaps I will go there)
Take an umbrella with you. It might rail later. (= perhaps it will rain)
The bus isn’t always on time. We might have to write a few minutes. (= perhaps we will have to wait)
The negative forms are my not and might not:
Ann may not go out tonight. She isn’t feeling well. (= perhaps she will not go out)
There might not be enough time to discuss everything at the meeting.
Compare will and may / might:
I’ll be late this evening. (for sure)
I may / might be late this evening. (possible)
Usually you can use may or might. So you can say:
I may go to Hawaii. or I might go to Hawaii.
Lisa might be able to help you. or Lisa may be able to help you.
But we use only might (not may) when the situation is not real:
If I were in Tom’s position, I think I might look for another job.
The situation here is not real because I am not in Tom’s position (so I’m not going to look for another job).
May is not possible in this example.
There is also continuous forms: may / might be -ing. Compare this with will be -ing:
Don’t call me at 8:30. I’ll be watching the baseball game on TV.
Don’t call me at 8:30. I might be watching (or I may be watching) the baseball game on TV. (= perhaps I’ll be watching it)
We also use may / might be -ing for possible plans. Compare:
I’m going to Hawaii in July. (for sure)
I may be going (or I might be going) to Hawaii in July. (possible)
But you can also say “I may go (or I might go) to Hawaii” with little difference in meaning.
Might as well / may as well
Rosa and Maria have just missed the bus.
The buses run every hour.
A : What should we do? Should we walk?
B : We might as well. It’s a nice day, and I don’t want to wait here for an hour.
We might as well do something = We should do it because there is no better alternative.
There is no reason not to do it. May as well is also possible.
A : You’ll have to wait two hours to see the doctor.
B : I might as well go home and come back.
Rents are so high these days, you may as well buy a house.
(= buying a house is as good, no more expensive)