We went in April and the weather was ok, cool, not too cold and not too wet. We did take ponchos (waterproofs) with us and wore jackets without jumpers. Later on in the day, when it got a little bit warmer, we only wore fleeces.
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We went in April last year and the weather was quite pleasant. Think we wore cropped jeans and long sleeved T shirts and just needed light jackets with us.