Most varieties of Azalea only bloom for about 4-6 weeks anyway, but if yours had dried out, unopened buds, yet the plant is healthy in itself, likely too much hot sun or shortage of water at some point caused this.

@Bamboo thanks. The plant is in partial shade. It shows up buds occasionally but the buds dry out within 4-5 days. There are no pests.

I don't suppose you know the full name of your Azalea, that is, which variety it is? Some do not cope at all well with high temperatures except in summer. Hot, dry air can cause this problem, though I've actually no idea what your temperatures are like there at this time of year.