Whether it rain or snows depends on many factors including temperature and altitude and that was very much the case yesterday evening.
In Cardiff the temperature at 7pm was 3 Celsius with rain, while in Tredegar it was close to 0 Celsius with snow.
Tredegar is over 1000 feet (300 metres) above sea level and generally the higher you climb the colder it gets - for every 100 metres the temperature drops by roughly 1 degree Celsius.
This is why snow is more likely over hills and mountains than on the coast.
Another thing to bear in mind is that heavy rain can lower the temperature and turn to heavy snow.
This is called evaporative cooling and is most effective when the wind is light; the temperature drops because the air isn't being mixed up by the wind.
Sunday's weather chart for Wales showing possible heavy snow for some areas.
There is some heavy rain on the way over the weekend and a risk of snow too for some parts of the country.
A yellow warning has been issued by the Met Office.
There is still some uncertainty in the forecast at the moment, but the greatest risk of heavy snow is on Sunday into Monday for mid and north Wales, especially on high ground but it could all change so stay tuned for updates!
So, Sunday will be wet with 10 to 20mm of rain and there could well be snow in mid Wales and the north but not much at all on the coast
Inland however, 5 to 10cm, 2 to 4 inches of snow is possible with more snow on higher ground, especially on the Berwyn Mountains.
In the far south and south west, it may dry and brighten-up during the afternoon.
Sunday night into Monday will see most of the snow in the north and north east but in the south there maybe a little sleet or snow.
Next week is becoming dry and settled for a time with some frost.
Rugby weather: in Paris, the weather for the rugby shouldn't be too bad on Saturday - the odd shower otherwise dry with light winds. Temperatures will drop to freezing and rise to 5 Celsius in the afternoon
Good luck to Wales and keep an eye on the forecast at home because things could change over the weekend.
Derek
