Welcome here.
I am hearing using coolers is only good during low humidity. May I know the range in which coolers are best over AC?
More Humidity with more temperature is culprit in summer months.
30-60 is ideal Relative humidity for a home.
For air circulation, open window to circulate air and regulate it between 30 to 60.
It depends on humidity level in daytime when temperature /heat is more and you have higher humidity levels.
You have to check at your place yourself.
If you are in room at some open place at top then cooler can work easily in high humidity also as fresh air available to you is more.
If fresh air is not available or circulation of air is not possible in a room then only humidity traps inside and it will be not be comfortable.
Data of humidity level is different at all places.
They show humidity level in average of whole city or an area.
July & August are worst hit months of monsoon with high humidity and temperature also.
You can run water cooler without pump at times or at regular intervals with help of a timer also if temperature is more than 40 and humidity increases from desired level for your comfort.
Each one has own comfort level.
Normally till May in Delhi, you can use coolers easily as humidity level even if increases for sometime, it goes away with heat in next few days. When regular humidity level increases above 60 and temperature is above 40 then try to be out or at open shadowed place.