Høstjevndøgn is the Norwegian word for the autumnal or September equinox. It marks the end of astronomical summer and the beginning of astronomical autumn in the northern hemisphere. 

Jevndøgn means equinox, and høst means autumn. The word used in English, equinox, comes from Latin: aequus (equal) and nox (night). The Norwegian term is directly related to Old English and Norse. Jevn is an adjective similar to “even” and can be used to describe a physical quality (en jevn overflate is “an even surface”), as well as to mean “equal”.

Døgn is a useful Norwegian word that doesn’t have an exact English translation but can both mean “a day” or “a 24-hour period”. 

It’s usually used in preference to the more common dag (“day”) when talking about the amount of time within a day and not to the day in general. So, for example, a store that is open 24 hours a day is described as døgnåpent, “24-hour-open”. 

Why do I need to know this? 

The autumn equinox is on September 23rd 2023. From that date onwards, the days will become darker than lighter. 

The Norwegian word for solstice is solhverv, from sol (sun) and hverv, an archaic word for “turning”.

Example

I dag er det jevndøgn, når dag og natt er like lange.

Today is the equinox when day and night are the same length.