Norway in May/early June or Sept? Route questions

One is spring, the other is autimn. It influences the freshness of nature - maybe water amounts of waterfalls. In Copenhagen Sept days can still feel like Scandinavian summer.

Travel wise I do not see restrictions at both mentioned travel dates for the areas mentioned.

Are you more interested in cities or nature? Any special interests?

Around Bergen a rental car can have several advantages. But in general all Scandinavian cities are car haters - except their owns.

The Norway Travel people say that early September can feel like Summer, just cooler in the mornings and evenings. You can see Autumn Colors. There are less tourists. I was there in August and it was quite warm. Look into booking a passage on one of the Postal Ships. The ship makes short stops along the way in the Fjords. Some friends did this and rented a car at one stop to try to find an old Family Farm. They drove until they thought they were close. They walk up to a house to ask if the residents had heard of their folks place. The Lady of the house spoke English and said yes and please come in Cousins! They had lost track of the other part of the Family that had gone to America after WWII. We do what is called "Dark" tourism and go to the battlefields and cemeteries and have found long lost relatives that way.

Looking at newer climate tables (not Wikipedia) I would be careful with optimistic weather assumptions in Bergen for September. The precipitation in this month in Bergen is nearly 50% of the annual precipitation in Copenhagen.

I can't speak for September weather.

We toured Norway the last 2 weeks of May and early June 2023. We flew into Kirkenes and traveled along the western coast south to Bergen on a Hurtigruten ship. After the 2nd day we were in drizzle/mist almost all the way to Bergen.

After a damp 2 night stay in Bergen we did our own do it yourself NIN with an overnight in Flåm and had glorious, sunny days all the way to Oslo and, also, while in Oslo. Doing the NIN actually puts you on the fjords surrounded by mountains

We then flew to Ålesund for 3 nights with drizzle on 1 day.

Sunset end of May is around 10:45pm, September around 8ish depending on dates

We did the entire trip without car rental, taking a couple excellent small guided tours by minibus in Flåm and Ålesund to to see more beautiful Norwegian scenery.

I'm sure you'll enjoy your trip in either season.

Jeanm has pointed out the one guaranteed difference between your two potential time periods: The days will be a lot longer in June. However, it's possible you won't find daylight an issue in early September; I usually begin to be bothered by the shorter days in mid- or late September.

The west coast of Norway, including Bergen, is very rainy. Heading there for outdoor activities or to admire the scenery is always a roll of the dice. You can increase your chances of enjoying the magnificent scenery by not rushing from place to place.

I've never heard that the Norway in a Nutshell scenery is appreciably better traveling in one direction rather the other other. What's tricky is finding lodging, especially around Flam, if you decide not to do the entire NiN route in a single day.

Thank you all for your feedback!

Jeanm-could you tell me what tours/companies you booked from Flam and Alesund that you enjoyed?

In Flåm we booked the electric minibus tour to Stegastein Viewpoint with FjordTous.com. The tours are timed for the ferry arrival from Gudvangen. Our driver/guide added some extra stops extending our tour from 90 minutes to about 2 hours.

In Ålesund, we booked the full day "Tour from Ålesund to Trollstigen" with LocalTrips AS. We chose a day with limited cruise ships in town and there were only 4 of us on the minivan tour. The owner Trond was an excellent storyteller and guide.

Trollstigen won't be opening until July 14, so if you want to see that (I found it a highlight) you should do September. We went in September for 18 days, and I only recall one day where it rained for any length of time. We rented a car and did a RT from Oslo to as far north as Farstad and as far south as Byrkjedal.