If you're hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Arc-1800: The hottest months are usually July and August, with an average temperature of 13°C, while the coldest months are January and February, with an average of -4°C. The rainiest months in Arc-1800 are May, December, November and January, with each month seeing an average of 189 mm of rainfall.