The prediction, reported by news agency ATS, is based on the number of postal votes received so far for this Sunday's federal elections, a figure which doesn't differ greatly from this time four years ago, when eventual voter turnout was just 49.1 percent.
Speaking to broadcaster RTS, political commentator Georg Lutz of the University of Lausanne said he expected voter turnout in French-speaking Switzerland to be slightly lower than in 2011.
But, as ever, the number of votes cast is predicted to vary between cantons.
According to ATS, Fribourg expects voter turnout to attain or exceed the 46 percent achieved in 2011, Geneva is predicting a figure between 43 and 45 percent, and the canton of Neuchâtel estimates a final turnout as low as 39 percent.
The Swiss-German part of the country is recording a slight rise on four years ago, however.
In Basel, some 40.3 percent had already voted by Thursday morning, against 37.1 percent the same time four years ago.
Switzerland has one of the lowest voter turnouts for parliamentary or presidential elections in Europe.
According to figures from Eurostat, only Poland, Lithuania and Romania have had a lower voter turnout than Switzerland in general elections in the past ten years.
Switzerland's 2011 figure of 49.1 percent was relatively high for the alpine country, which registered 48.3 percent in 2007 and 45.2 percent in 2003.
That compares with 66.1 percent turnout for the UK's general election earlier this year, 71.5 percent in Germany in 2013, 70 percent in Ireland in 2011, 80.4 percent in France in 2012 and 81.4 percent in Iceland in 2013.
At the lower end of the scale, Bulgaria registered 51.1 percent in 2014, Lithuania mobilized 52.9 percent of the population in 2012 and Poland attracted 48.9 percent to the polls in 2011.
In Belgium, Luxembourg and Greece, voting is compulsory, though Greece only achieved 56.5 percent in this September's snap election, a record low.
The low turnout of Swiss voters at federal elections is generally attributed to the country's bottom-up system of governance, in which the people are regularly asked to participate in referenda.
“In Switzerland we participate in numerous votes, therefore certain people become selective,” commented Lutz to RTS.
Generally, he said, there are “10 to 20 percent who vote all the time and the same amount who abstain each time.”
Average voter turnout in the four Swiss referenda held in 2014 was 52.4 percent, higher than in previous years partly because of the 56.4 percent participation rate in the February 2014 referendum against mass immigration.
That initiative backed by the populist Swiss People's Party saw 50.3 percent of voters casting their ballot for immigration quotas.