Best weather for Jungfrau & hikings ?

I am for a 2 to 3 month Europe trip and I am flexible on the dates.
I understand going up to Jungfrau will be a waste if it is cloudy.

I know the daily weather is unpredictable but is there any month or season in the year when there will be lesser cloudy days generally ?

Best is usually first two weeks of September

I'm planning to buy Good Morning or Good Afternoon ticket to Jungfrau. Now in July, which one has better chance for a good weather?

Always in the morning, regardless of time of year.

Thanks, Kim Il

Thank you for the advice.
I wish to avoid summer months for my Europe trip and I want to go in Spring for the Holland Tulips festival. Beside September, which is the best month between March to June ?

If you want to visit the mountains, March and April are not good. It is "mud season" in the Alps and most of the restaurants, hotels, etc in the lovely mountain villages are closed down for a break between ski season and summer. If March through June is your only choice, then go as late as you can in June. This year it was still snowing and many of the high mountain transports were still closed in June. The Jungfraujoch train runs year round (weather permitting) but when the weather is cloudy, rainy, or snowy you will waste lots of time and money to see nothing.