Dear Mallika,
Spring starts from Mar to May and Summer is from June to Aug ... So, according to me you will still have little rainy season along with wind and cold ... but not like deep winter in April ... To be sure, the weather in Luxembourg could not be confirmed by anyone due to climate change everyday dear ... If you ask me, I will say it is really good to be in Luxembourg during the months of June to Aug in summer season ... As this is the school vacation season in Lux...

... As you have kids, better to travel during summer so that you can even travel to Germany, France, Switzerland which is all nearby to Lux and make suitable plan according to that
only if you travel during summer ... Luxembourg is really a beautiful and lovely country ... You can see all the beautiful view and enjoy all river side views only if you come in summer else it will be little cold ... I will attach the photos of river view of Luxembourg in Esch-sur-Sure ... else you can search in google ...

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