Weather Averages and Climate in Latvia. Latvia has nice weather in the summer and it gets pretty cold in the winter. Latvia experiences reasonably mild winters, beginning in January and ending in March. Average temperatures range from 10°C (50°F) to 15°C (59°F) in winter, and sometimes getting as cold as -6.6°C (20.1°F) to -2.8°C (27°F). Continuous snow cover in Latvia lasts an average of 82 days, with an average of 177 frost-free days. April and July are two of Latvia's hottest months, with average temperatures of 24°C (75.2°F) to 34°C (93.2°F). Due to Latvia's close proximity to the sea, summers tend to be humid and somewhat rainy. Average annual rainfall in Riga is 566 mm (about 20 in.), with an average of 180 rainy days annually.