Grahame Madge, Met Office spokesman, told HuffPost UK: "There's a number of warnings for wind today and rain warnings tomorrow".
Rainfall totals could reach as high as 150mm over the Brecon Beacons, almost as high as the monthly average of 170mm for Wales.
The highest speeds were recorded on the Isles of Scilly in the early hours of Friday morning, while 60mph gales were recorded in Camborne in Cornwall and Milford Haven in Pembrokeshire.
The storm is wreaking havoc on travel arrangements, with certain flights being canceled on Friday morning at Cardiff and Exeter airports.
Lough Atalia rd, Salthill and associated roads from the entrance to Mutton Island to Threadneedle rd, Inbound Slip Lane on the Dublin rd, Eyre Square (Meyrick Hotel), Dock Road, Victoria Place, Queen Street, Salthill & Toft carparks, and Silver Strand will close.
Both Met Éireann and Midland Weather Channel have issued severe weather warnings ahead of Storm Callum's arrival in Ireland tonight.More news: French police investigating after Interpol president reported missing in China
More news: Virat, Jadeja Cross Mega Milestones on Day 2 vs Windies
More news: Woman Who Identifies Herself As A Rape Survivor Confronts Lindsey Graham
Storm Callum forced a meeting of the National Emergency Co-Ordination Group this afternoon and Met Éireann has issued its latest update on the expected storm impact.
Motorists are being warned to exercise extreme caution along all road networks as there have been numerous reports of fallen trees on routes nationwide.
Throughout Friday and Saturday, areas covered by the warnings could see between 50-100 mm on Friday and 50-80 mm on Saturday. "Elsewhere, however, the winds should remain below warning thresholds".
Windsor, the scene of Friday's royal wedding, looks set to escape the worst of the storm.
Guests arriving at the royal wedding in a windy Windsor had to hold on to their hats, with gusts of up to 32 miles per hour.
A guest stoops to collect her hat that blew off in the wind as she arrives for the wedding of Princess Eugenie to Jack Brooksbank at St George's Chapel in Windsor Castle.