Group 1 - The winter of this year has seen significant temperature fluctuations, with the coldest periods (Sanjiao and Sijiao) now passed, and the focus shifts to the upcoming Wujiao period [1][9] - During the Sijiao period, temperatures in many regions, especially in northern China, were notably lower than the historical average, with some areas experiencing drops of over 4°C [3][4] - The upcoming Wujiao period is expected to have weak cold air activity, leading to a relatively stable weather pattern with more sunny days in northern regions, although some areas may still experience haze [3][4] Group 2 - A new cold air mass is forecasted to impact central and eastern regions from January 29 to 31, causing temperature drops of 4-6°C, with localized areas experiencing drops of over 8°C [4][6] - This cold air will also bring widespread rain and snow, particularly affecting northern regions with significant snowfall and mixed precipitation in parts of southern regions [6][7] - Overall, while temperatures in the northeast will remain low, most other areas are expected to see temperatures close to or above historical averages, indicating a warming trend as Wujiao progresses [9][11]