According to information available on the IPMA website, the weather for the mainland for the period between December 31 and January 2 includes "higher-than-normal temperatures for the month of December" (with 1°C to 6 more °C) and also less rain than usual for the time of year.
Maximum temperatures may reach values between 18°C and 22°C in some places in the north and centre coastal regions in a large part of the southern region.
For January 2nd, a small decrease in the maximum temperature values is expected, but even so, values between 18°C and 20°C should be reached in the Alentejo and Algarve, and in the rest of the country the maximum temperature will vary between 11ºC and 17ºC, with the lowest values predicted for the extreme north of Portugal.
For New Year's Eve, a “stable weather situation, with no precipitation” is expected, with high clouds and temperatures ranging approximately between 8°C and 13°C on the coast and between 2°C and 8°C inland.