Out of the blue and Too soon

Out of the blue adverb - In a way that was not expected.

Too soon and out of the blue are semantically related. In some cases you can use "Too soon" instead an adverb phrase "Out of the blue".

Too soon adverb - Before the usual time or the time expected.

Out of the blue and too soon are semantically related. Sometimes you can use "Out of the blue" instead an adverb phrase "Too soon".