General clues and options for aviators:
1) Area forecasts exist in most places so you get a general feel for what the winds aloft / surface winds are doing.
2) Smoke from fire, and ripples on the water show the direction of the surface wind where you want to land
If the two points above are available, you can make a standard overhead join (cross the threshold you think is in use at 500ft above circuit height and then make all turns in the circuit direction of that runway, descending to circuit height on the dead side of the airfield) and check the wind sock or wind tee on the ground to confirm your suspicions. If the windsock says otherwise, you use the other runway.
3) Make a radio call on the unattended frequency for the airfield and normally, anybody in the circuit will reply with their intentions including the runway in use
The above is the most accurate way of confirming you have the best runway in mind. Going in on a random runway and going around because you've got a beast of a tailwind is ill-preparation and not great airmanship.
Of course, all of the above is for uncontrolled airfields since airfields with control will give you the runway in use.
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