The American custom has now become established in the Scandinavian country as a carnival-like autumn tradition after struggling for many years to be accepted.
The proportion of people in Norway who mark the occasion increased from 15 percent to 30 percent between 2012 and 2018, Oslo Metropolitian University's (OsloMet) research institute SIFO has found.
Families with children and young people make up the majority of people who take part in Halloween, which one researcher described as being seen as an autumn-time family festival.
“Over the course of the last 30 years, we have gone from a ritual marked as an American import and associated with over-consumerism to a new, culturally-adapted, carnival-like ritual,” OsloMet culture historian Virginie Amilien says in the university's article.
Since 2015, discussion of Halloween in Norway has moved from being framed around whether it should be celebrated, to how it should be celebrated.
“There's now more agreement in society over how Halloween should be celebrated,” Amilien said, noting in particular what Norwegians eat and wear on October 31st.
Stores throughout the country are heavily stocked with Halloween goods in the weeks leading up to the day, but Norwegians do not necessarily mark Halloween extravagantly, according to researchers.
Most people spend less than 250 kroner on Halloween, the report states.
“A lot of costumes are re-used and many try to consider the environment by not buying new things,” Amilien said.
A five-fold increase in pumpkin sales in Norway between 2012 and 2018 is another reflection on the growth of interest in Halloween.
Meanwhile, the number of people who make costumes increased from 5 to 13 percent, according to SIFO's research. The proportion who re-use costumes increased from 15 to 22 percent.
“It's also the sense of doing something together which is important. You make costumes with your children, and time with your children is valuable,” Amilien said.
The number of people who said in the survey that they left the house on Halloween to avoid trick-or-treaters increased from 6 to 13 percent, meanwhile.
The full SIFO report can be found (in Norwegian) here.