The Arnathian calendar features 10 months, consisting of 5 weeks of 6 days each. This makes for a total of 300 days in a year.

The hottest day is usually in the 3rd week of the 7th month, and the coldest the 3 week of the 2nd month.

Given that there are two suns around which Arnathia orbits, there is also a slight variation every other year, with odd numbered years being about 5% warmer and even numbered years about 5% cooler. [img:2054220|right|400]

The biggest variation in temperatures is due to the path Arnathia takes around its suns. This 14-year cycle creates a +/- 15% variation in temperatures, as well as a +/- 20% variation in the number of storms, and severity of those storms. At the beginning of the cycle, the planet is furthest from the suns, so storms are less likely and the severity of those storms is diminished. At the middle of the cycle, when the planet is closest to the suns, storms are 20% more likely and the severity of those storms is likewise increased by 20%.

The pictured stone calendar depicts one year. Symbols mark the shortest and longest days of the year, as well as the beginning of the spring and autumn months. Also, there is traditionally a depiction in the 2nd week of the 8th month of when the Cataclysm occurred. These features are common across Arnathia, and local versions of these calendars may add depictions for local events, festivals, or commemorations.