Monday 12 March 2012, 16:19
Well it was very much a case of mixed fortunes over the weekend. Most of Wales enjoyed turned out sunny yesterday with temperatures in Usk soaring as high as 17.7 Celsius on Saturday.
However, some places stayed grey, cool and misty with fog patches on the coast and at Mumbles Head the temperatures struggled to reach 10 Celsius.
The reason for the generally dry and settled weather is high pressure. Under high pressure the air sinks and warms and this can create a temperature inversion.
James Street went for a walk in the hills overlooking Treorchy and the rest of valley`s.
Normally temperature falls with height but with an inversion it rises so that the top of a hill can be much warmer than the valley below.
This has been the case today with cloud, mist and fog trapped beneath the inversion, while above the inversion, on higher ground, it is warm and sunny.
At night if the sky is clear with little wind the temperature can drop like a stone. Last night for example, the temperature in Tredegar fell as low as 2 Celsius with ground frost but with plenty of sunshine today the temperature has soared to over 16 Celsius.
There's more dry weather to come over the next few days but there are signs of a change on the way later in the week. The high pressure will move away and it is expected to turn more unsettled with some rain.