案の定【あんのじょう】

案の定 is an adverb meaning "sure enough", "just as I thought": what happened is what the speaker had predicted, and usually feared. It stands at the head of the clause that reports the outcome, often after a ～たら clause that sets up the cause.

The outcome is a fact that has now come true, so the verb after 案の定 is in the past, or describes a state you have just found. It cannot introduce a prediction.

• × 案の定雨が降るだろう → きっと雨が降るだろう

案の定 or やっぱり

やっぱり and やはり confirm any expectation, good or bad. 案の定 nearly always reports something unwelcome, with a note of "I knew it". For a good result, やっぱり is the natural choice.

案の定 is a little more formal than やっぱり, and it is at home in both speech and writing.