Fire crews are currently tackling a blaze at a timber manufacturing unit in the village of Pentrebeirdd, Guilsfield, in Welshpool.
Mid and West Wales Fire & Rescue Service received the call at 6.10pm. Seven appliances and an aerial appliance remain at the scene. Nobody is injured.
A grass fire that broke out in Swansea yesterday evening covered 30-35 hectares - the equivalent of 70 football pitches.
Gwyn Lewis, station manager at Mid & West Wales Fire and Rescue Service, told ITV Cymru Wales fire crews received 160 alerts for the same incident - the first at 8.20pm.
Welsh firefighters have dealt with more than 250 grassland fires over the last week, with incidents from Anglesey to the South Wales valleys.
"More than 300 calls" were received by Mid & West Wales Fire Service between 7pm last night and 2am this morning about the flooding. The service says the worst affected areas were Kidwelly, North Gower, Narberth, Solva and Pembrokeshire.