雪のために飛行機が遅れるか欠航しますって英語でなんて言うの？

Quite often, there is a lack of precise detail about weather conditions in official announcements. Instead of identifying exactly what the weather problem is, the announcer would be far more likely to say something like:

"Due to adverse weather conditions flights may be affected by delays or cancellations."
If there is a complete lack of information from the airline about a flight that has not yet arrived, you may give a vague, personal opinion such as:
"There may be a problem with the flight because of the weather."

Severe weather conditions is usually recognized and known when relating to flights.
Flights are only cancelled when it's a serious issue, a severe weather condition will imply that it relates to snow, or any other drastic weather.

In order to explain that a flight may be delayed or cancelled because of heavy snow, you can say:
The flight may be delayed or cancelled because of snow
This is the most simplest way to say it.
May be - This means might be
Because of - Due to

You can also say:
Heavy snow may result in the delay or cancellation of the flight.
This is a very formal statement, perhaps given as an announcement in an airport.
May result in - This means that it might happen
Delay or cancellation - noun form of delayed or cancelled.

I hope that helps!

examples
"I cant fly due to delays because of the snow."
or
"The snow has left many flights cancelled."
or
"The flight has been delayed."
or
"The snow has been really heavy, they have cancelled all flights due to the bad weather."

There are many ways you can explain this but you want to use a word such as 'may', 'uncertain', 'some' ,etc to show that you are unsure as to if the flight will run on time.

What can usually cause a flight to either be delayed or even be cancelled are weather conditions. If there is heavy snow for example, the runways will be full of snow. This can make it very difficult for airplanes to run through before takeoff. So, airline managements do delay flights until the snow has stopped and the runways have been cleared, or they cancel the flights altogether and reschedule them. So, if you have been affected by such an occurrence, you may tell someone as follows:
My flight may be delayed or cancelled due to heavy snow.
or
Heavy snow on the runways may result in the delay or cancellation of my flight.
or
My flight may be delayed or cancelled due to severe weather conditions.