can, could, may, might

[Stella Avaro]

What´s the difference between can be, could be, may be and might be in context?

[Casiopea]

According to Oxford,

MAY/MIGHT for something possibly true or an uncertain prediction or intention. MAY is stronger than MIGHT.

EX: You may/might get stucked in traffic if you don't go early.

CAN/COULD for possible future actions.
=> CAN = stronger possibility
=> COULD = distant possibility

EX: We can/could have a party (suggestion)
EX: We may/might have a party (uncertain intention)

FOR UNCERTAIN PREDICTION about the future, use may/might/could NOT can.

CAN as generally possible
EX: Smoking can damage your health.

POSSIBILITY into the past
EX: May have missed the train (perhaps) ( 35%)
EX: The train might have been delayed (perhaps) 30%
EX: The letter could have got lost in the post (it is possible 50%)

[la_patata]

I also have a question: if we speculate about future events, can we use might/could interchangeably? I have to teach pre-intermediate students... In the book, there are may, might and could mentioned. However, our native speaker is strongly against using "could" in this situation...

For example, in this sentence: It might rain tomorrow., is it possible to use "could" instead?

[Luka Nieto]

I've seen different responses many times. Is it different in different countries?