The present continuous can be used to express future tense. It is especially common in conversation. However, there are two cases in which it is never used to express the future.
One case is with predictions. It is not used in a sentence such as It will rain tomorrow. The sentence It is going to rain tomorrow is also correct. However, the use of the present continuous such as in the sentence It is raining only applies to the present tense.
Another case in which the present continous is not used is the result cause of conditional imperatives. An example is Take an umbrella or you'll get wet. The sentence can also be expressed with going to, i.e., Take an umbrella or you're going to get wet. The use of the present continuous in such a sentence is incorrect. The sentence can also be expressed with the conjunction if. In the sentence If you don't take an umbrella, you'll get wet is not expressed with the present continuous.
The present continuous is fine in sentences such as I'm meeting them tomorrow and The movie is coming out soon. However, with predictions and conditional imperatives, the present continous is never used to express future tense. In certain cases, the present continuous cannot be used to express the future.