The only signs of the Hour communicated by God through Prophet have reached us through Quran.
Other extra-Quranic “signs” can be seen as interpretations by early Muslims in the 7th-8th centuries of events happening during their lifetime. In literature, such predictions are generally referred to as “Vaticinium ex eventu”, or “post eventum”, such as when someone noticed Umayyads building tall buildings or adopting Byzantine architecture, they invented it as a Hadith about “sign” of end of times, and the professional storytellers managed to spread it when the demand and consumption of “Hadiths” was quite high in the new empire. The role of such story-tellers is well-documented.
Since many believed the end times were imminent, numerous Hadiths then emerged that reflect their thoughts and beliefs about signs of the end times.
Considering there were multiple Fitnas, civil wars, and the rise of sectarianism and theological warfare during that time. A lot of these “signs” seem to be descriptions of activities that occurred to the Early Muslim societies that were going through strife.
If you analyse all these “signs” narrated in the hadith books, you will notice that there is nothing unique or extraordinary in them. Such signs have always been present in every human society.