Ha!...as was proved at Cadair - where it was 30 deg C a 6 minute gap unfathomably developed, push it up to 35 degree I say....
Anyway more importantly - just spoken to Gilbo re: today's route - you'll love this.
So they took road to Ogwen and were going to head up Cwm Tryfan and down to Cwmffynnon and Pen Pass, anyway that was changed en-route and they ended heading up Bochlwyd and down to PenGwryd and up road to Pen Pass, so within first 18 mile there were around 15 of road - gutted I didn't do it.