Met Office officials confirmed that parts of the UK were far hotter than nicer places such as Sicily and Rome in Italy, and Athens in Greece, with more heat to come
The main idea is that despite being winter, the UK experienced unseasonably warm temperatures on Christmas Day, exceeding those of more traditionally warm destinations like Athens, Rome, and Sicily. This unexpected heatwave is predicted to continue into Boxing Day. The article uses the phrase "White Christmas?" rhetorically to highlight the incongruity of warm weather instead of the typical snowy Christmas conditions.