Allah said:

فَأَرْسَلْنَا عَلَيْهِمْ رِيحًا صَرْصَرًا ...

So We sent upon them a Sarsar wind.

Some said that this was a strongly blowing wind; others said that it was a cold wind.

It was also said that it is the wind that makes a noise.

The truth that it was all of these things, for it was a strong wind that was an apt punishment for their being deceived by their physical strength.

It was also intensely cold, as Allah says:

بِرِيحٍ صَرْصَرٍ عَاتِيَةٍ

with a Sarsar wind! (69:6),

meaning a very cold wind.

It also made a furious sound. Additionally, there is a famous river in the east which is called Sarsar because of the noise it makes as it flows.

... فِي أَيَّامٍ نَّحِسَاتٍ ...

in days of calamity,

means, consecutive days.

سَبْعَ لَيَالٍ وَثَمَـنِيَةَ أَيَّامٍ حُسُوما

seven nights and eight days in succession, (69: 7)

This is like the Ayah:

فِى يَوْمِ نَحْسٍ مُّسْتَمِرٍّ

on a day of calamity, continuous, (54:19)

i.e., the punishment began on a day which was of evil omen for them, and this evil omen continued for them,

سَبْعَ لَيَالٍ وَثَمَـنِيَةَ أَيَّامٍ حُسُوماً

seven nights and eight days in succession, (69:7)

until they were destroyed, every last one of them, and their humiliation in this world was joined to their punishment in the Hereafter.

Allah says:

... لِّنُذِيقَهُمْ عَذَابَ الْخِزْيِ فِي الْحَيَاةِ الدُّنْيَا وَلَعَذَابُ الْآخِرَةِ أَخْزَى ...

that We might give them a taste of disgracing torment in this present worldly life. But surely the torment of the Hereafter will be more disgracing.

meaning, more humiliating for them.

... وَهُمْ لَا يُنصَرُونَ ﴿١٦﴾

and they will never be helped.

means, in the Hereafter, just as they were never helped in this world, and they had no one who could protect them from Allah or save them from His punishment.