We will be spending 5 nights in Paris the second week of September. Is it (usually) still hot enough to need air conditioning in the hotel we choose? I need air conditioning any time it gets close to 80 degrees. But I'm noticing rooms (in the Marais) without air conditioning are significantly (up to 50 percent) less $.
Also, for rooms that do have air, are they those awful noisy units stuck in the window that you often find in mid-priced American motels?
I normally travel in September, and in my experience having A/C in Paris at that time of year would be a really good idea. I'm willing to pay a bit extra for that, as having a good (and comfortable) sleep is important.
The type of A/C installed tends to vary between hotels. Most of the A/C units I've encountered in Europe are this type - https://www.energy.gov/energysaver/ductless-mini-split-air-conditioners . They're not overly noisy.
Records for Sept 2018 show 3 days in the 2nd week were 84F or higher.
Depending on what fans may be available and whether there is cross-flow ventilation, may make a room comfortable for the overnight sleep time---- all the overnight lows were in the mid 50s
https://www.accuweather.com/en/fr/paris/623/month/623?monyr=9/01/2018
Last year is no guarantee for this year
I would not book a hotel in September without it. Lots of hotel rooms have no cross currents and get very hot in warm or hot weather.
May-September I would not stay in Paris without A/C. Experiencing one heatwave in Paris in a non-A/C hotel taught me that. Hell, this year it was very warm throughout October. Keep in mind Paris is stone and concrete and asphalt and it really absorbs the heat of the day and radiates it back out even at nighttime. I've never been more miserable in hot weather than I was in that hotel room in Paris without A/C when it was 90 out at 11:00 p.m.
If 80 degrees if your limit without A/C you're absolutely going to want to book a room with A/C. In my experience most A/C units in hotels in Europe are above-the-door models that aren't too noisy. But if it's an issue I'd call a prospective hotel to double-check.
An added advantage of AC on warm September nights is that the light sleeper can keep the window shut if there is neighbourhood street noise. I love Paris in September, by the way.
I find September to be really nice in Paris. Very comfortable days and cool nights. If you find a place that opens on to a quiet courtyard, you can open the window to cool down at night (then close the curtains to keep it cool while you are out during the day). If the room opens onto a busy street, it may be too noisy for both cooling and sleeping.
Using September 2018, with the hottest summer for 30 or so years, after the worst winter for many years, as the example may or may not be accurate for this year.
We were in Paris Sept. 2017 and never needed AC. Weather was very comfortable (high 60s - mid 70s) and with the window open, it was perfect. However, I have been in Paris when it was in the 90's and no number of open windows helps then. The stone buildings absorb the heat all day then radiate it back out at night so it never really cools down. If you really don't do well with heat, I'd say you might want to pay for AC but you'll probably only need it a couple times.
Because you mention that you need air conditioning any time it gets close to 80 degrees (possibly for health reasons?), I wouldn’t gamble on the weather in September. I was in Paris last September 7-10, and it was mid 80s during the day.
If you let us know your budget, perhaps we can make some recommendations for Marais hotels with air con in your price range.
Generally - in Paris - yes.
