When to go to Paris: May vs. September

I've been in both months, and don't really think there is an advantage of one over the other. When I was there for 2 weeks in September 2013, there were only maybe 4 days that it didn't rain and maybe 2 of those when it was actually sunny. In May 2015. The weather was very nice - I think I wore my raincoat only once in 2 weeks.In September 2017, the weather was much nicer than in 2013 with maybe just 2 or 3 days of rain. I should say that it rarely rains all day, but on the days it does rain, it could be cloudy all day. It is a little cooler in May and I found there was less humidity.

September is a very popular month for tourists, conventions, trade shows, and fashion week. So, it can be very crowded and expensive - best to book lodging early. May is also popular, but there is not quite as much other stuff going on. The big sights are crowded just about any time of year.

Given all of this, I still think I prefer September, and would even consider October. I think it really depends on when it is best for you to get away. I'm retired so can go whenever I want.

More daylight hours in May.

We have only traveled to Paris in September. Paris has similar weather to where we live (Seattle area) and we appreciate less precipitation in September. We didn't experience humidity, but it can happen. It's a personal preference.

If you're there on the weekend of European Heritage in September, many otherwise-inaccessible locations are open for free. But as noted above, hotel availability is tight (and expensive) because of conventions in September.
So -- go to Paris in either month. Or go in both! As in the song, "I love Paris every moment/ Every moment of the year"

I would go in the month when airfare and lodging are less expensive than the other month. How do the numbers look?

Weather will likely be pleasant in both months and crowds will probably be similar, but check prices and hotel availability for your desired dates. Paris is notoriously busy and hotels can be more expensive in September. I also agree that a couple of additional hours of daylight can make a big difference and it stays light later in May than in Sept.

September is the nicest month and also most expensive for hotels and such because of its popularity. If I had the choice I would always be in Paris Sept/October. We have often traveled in May because it was the month we could get time when we were working; it is also lovely and not too hot, but we have also had weeks of rain and chill at that time of year.

I, too, have traveled in both May and September. I'd choose either for a return. As others have indicated September is a busy convention month. I did find on my May trip that there seemed to be more school field trips in museums and other places. I didn't notice as much of this in September so maybe at that time of the school year they are not ready for field trips yet.

I'm not sure where you are from but early Sept can still have some very hot weather. I assume late May can be warm as well - I've only been the 1st week of May. If you are going to be there at either of those times I'd consider making sure your hotel has AC if you are not real tolerant to hot weather.

I vote for May, more specifically, the second half of May vs Sept.

Late September and into mid-October had hot weather this year - mid 80s.

I think either is a fine time to visit-- if you're here May 1, keep in mind it's a big holiday where lots of things close (i.e. lots of places that close only Christmas Day and New Year's Day and May 1). There are several other holidays on the French calendar in May too. September, as others have noted, is the single busiest time of the year for trade fairs and Sept. fashion week (which is really fashion weeks between all the different iterations).

I like May. Flights are cheaper and so are hotel costs in my two May visits. The only downside is there seems to be more transportation strikes I’ve experienced in May. They usually don’t last long but can make for last minute changes if you’re on a schedule. Sign up for STEP( smart travelers with USA consulates) and they email you details as they become available.

Ive been twice in May, and I loved it! Great weather, not too crowded, great prices for airline tix, Paris in the Spring is simply spectacular!

Happy Travels💫✨

I was once in Paris for the second half of April, left on May 2. The whole city was in bloom, trees were covered in pastels and heavenly-scented lilac bushes were in flower. I don't know if that lasts through May. I don't know that room prices are higher in September but you do have to book early. One thing to consider is that the third weekend of that month is the European Heritage Days (Les Journees du Patrimoine). Many state buildings are open to the public and the museums (public, not private) are free. I happened to land on that weekend and got to see the inside of the Assemble Nationale, the Senat (Luxembourg Palace) and the Paris municipality (Hotel de Ville) as well as a couple of embassies housed in private mansions. The lines are long, but worth the wait. In late September you may get autumn colors.

I'd give the edge to May because it's spring and a good time to see flowers in the gardens. I love September too, so don't worry if you end up "having" to go in September.

Long days, shouldn't be hot at night, gardens in bloom...May is the obvious answer but September would be my second choice. Afterall, how many songs can you think of about Paris in the Fall?

Richard has it , it is always Paris in spring . This iconic song by Vernon Duke was supposed to be " May in Paris " , but due to the musical construction , two syllables were needed for the first word in the lyric , so we have " April in Paris " . The best and sweetest version I have ever heard , close your eyes and dream while you listen - https://m.youtube.com/watch?v=u2OkHbT5yFQ

Lest I forget , Autumn is unique here - https://m.youtube.com/watch?v=WyfFxkyLsQQ