In reply to Flamingsarah:
Yeah, totally impossible to say. It genuinely could be a summer-like heatwave, or full-on winter in the hills.
Mixed weather is most likely, but there is often a good settled spell sometime during April.
As said it will be midge-free - but there will probably be ticks around.
If you can't leave it last-minute to decide whether to go, plan for all eventualities - there's plenty to do around that way if you aren't only interested in climbing.