beware of upper winds

today at dawn it was clear sky, no wind, no turbulence. sometimes is like this at dawn, when i fly.
i flew 2 of my light gliders to 200 meters for several flights. pleasant flights.
then i launched my 2 meters radian sailplane that flies good too.
this time i decided to climb to 300 meters (some 1,000ft). as the sun was low at the east, i made a large turn starting from the north and ended up at the southeast. but then the plane didnt glide towards me. even began to move backwards, so i put it on a gentle glide to penetrate the wind. took me a long time to bring it back! at 100 meters began to move forward by itself, but with some turbulence.
i have faced high winds before, with some wind down here, but this time i didnt have any clue of a strong wind up there (clear sky), whilst down here there was no wind at all. zero. zilch. next flight launched facing the wind and kept the plane upwind, so there were no problems.
so, dont think that no wind down here means no wind-or some but not much-up there. but this never happened to me