Can the aurora be seen only on sunny days?

I can't. Aurora observation has a lot to do with weather conditions. Clouds are thin on sunny days and will not block the aurora, so the probability of seeing the aurora is much greater than that on cloudy days. Aurora mostly appears 90 to 130 km above the earth, and the clouds are below 10 km, so as long as there are clouds, the aurora will be affected. But even on sunny days, the aurora may not be observed; In addition, the darker the surrounding environment, the more conducive to the observation of aurora, so it is more ideal to stay away from urban lights.