Saturday
Scattered showers from dawn across Ireland and Scotland, these showers increasingly frequent and locally heavy, a risk of thunder in central/east Scotland and northern parts of Ireland afternoon. England and Wales start drier, a few sunny spells here and there, but then some patchy rain approaches from the southwest. This rain will gradually spread across southern England into the later afternoon, heavy bursts increasingly common, with extended heavy falls likely in Devon and Cornwall. Northern England stays dry with sunny bursts until the evening. Highs of 23C in the southeast, 16 to 18C for many, but only 12C in the northwest.

Saturday Night
The showers over Ireland and Scotland tend to ease, a few scattered spots lingering here and there. The rain in southern England pushes northward, brining widespread extended heavy falls to most of England and Wales through the later overnight hours. Some of this rain will likely linger over eastern Ireland as well. A notable easterly wind will build in northern England and southern Scotland. Lows at 7C north to 12C southeast.

Sunday
Extensive heavy rain from dawn across north Wales and northern England, a gusty easterly wind here as well. The rain will gradually break into showers, but heavy bursts are possible all day and only later will there be extended breaks. Southern England will have scattered showers, mostly in western areas, a few sunny spells breaking out too, best in the southeast. Scotland likely stays driest, a few scattered showers; the southeast may catch the northern edge of the broader area of rain. Showers in Ireland too, these frequent and heavy afternoon. Highs to 17C southern England, nearer 11 to 13C central and northern areas, locally 9C northeast.

Monday
A mostly cloudy but largely dry day across Ireland. Similar conditions in Scotland, but with showers arriving to the far north and spreading into the central Highlands with time. Southern Scotland and northern England likely stay dry with plenty of sunny spells. The remnants of the front from Sunday continue to bring showery rain to Wales and central England, these trending southward. A risk of heavy afternoon showers in southern England. Highs of 17C in the south and 12C in Scotland, though 8C in the far north.