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  • Diwrnod oeraf Mehefin

“Ni chafwyd diwrnod oerach yng Ngorffennaf na dydd Iau yr wythnos diwethaf [18 Gorffennaf 1946] ers deugain mlynedd a mwy, yn ôl rhai o’r garddwyr profiadol ar lannau Meirion. Syrthiodd y tymheredd mor isel fel y bu’n rhaid cynnau tân mewn nifer o dai gwydrau. Pryder llawer o’r garddwyr yw na cheir haul i roi gwrid ar domatos cyn iddynt syrthio.”[1] Meddai'r meteorolegydd Huw Holland Jones:

it was definitely July 18th that was the cold day, actually a couple of days leading up to that date. The weather log for July 1946 tells the story. A low pressure covered the UK from the 14th to 20th July, an unusually long time. drawing in a N, then NW airstream across Britain. This was a cold and cloudy airstream, and any clear spells at night would lead to very low minima, as was the case. Also unusual was the fact the low developed over the North Sea, not a warm place!, then moved SOUTH WESTWARDS ( the opposite direction to the normal track of a low) to settle over N England. You can follow its progress at http://www.wetterzentrale.de/topkarten/fsslpeur.html.[2]

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  1. Y Cymro, 26 Gorff 1946 (drwy law Haf Meredydd)
  2. Huw H. Jones ym Mwletin Llên Natur rhifyn 70