Packing for Paris in the spring may leave you a bit puzzled. April is the month with the highest average rainfall at 33 mm (1 and 1/3 inches), and May has the second highest average at 30 mm (1 inch). Temperatures in April average 8 degrees C the low and 15 degrees C the high, whereas in May, the averages are 11 and 20 degrees C (53 and 68). The humidity and cool weather could make you literally feel cold to the bone, so you'll need to make sure you have certain items in order to have a pleasant stay in Paris. To start off, be prepared to wear layers and always carry an umbrella.
Scarves, scarves, scarves
Keeping your neck warm and covered will keep a cold away while you're in Paris. You should pack two thin wool scarves or pashminas and two cotton scarves; a simple one of each for daytime and a dressy one of each for dinners and other dress-up occasions.
Pack for warm feet and hands
Be sure to have a few pairs of tall wool socks to keep your ankles warm while you're sightseeing as well as undershirts and a pair of leather gloves to keep your core and hands dry and warm.
Pack for dry feet
Rain boots, low-heel leather boots and/or comfortable water-resistant sneakers will keep your feet warm and dry. If you're unable to find rain boots in your local shop you'll be able to find rather inexpensive (and stylish) ones in Paris. As far as leather boots, it is best to walk around in low-heel or flat styles because of the many cobblestone streets and uneven sidewalks all around the city.
Pack waterproof outer layers
Bring along a raincoat, waterproof coat or leather jacket. Not all raincoats are waterproof, but pack a regular raincoat or leather jacket for dress-up occasions and a waterproof raincoat for sightseeing trips. In addition, wear thin wool sweaters under your coat to keep you warm.
Remember to have some nice outfits for a night out
Generally men should pack three dress shirts and one jacket to go with khakis or jeans and women should have three nice outfits. Paris makes many people feel like dressing up. Pack a pair of nice shoes--closed-toe--to go with your outfits.
Tips and Warnings
If you choose to wear high-heel shoes, keep in mind that there are many cobblestone streets and uneven sidewalks all over Paris. These are charming, but watch out so you don't twist your ankle. If you'll be strolling below street level along the Seine (nice idea before or after dinner), you might want to take a pair of flat shoes in your bag to change into.
Wool gloves don't keep your hands very warm in the humid, cool weather so you'll be more comfortable in leather gloves.
Umbrellas and scarves are available for purchase all around Paris should you need extra ones but prices vary widely, with the least expensive umbrella at around 5 Euro. Scarves at tourist spots sell for about 6 Euro to 8 Euro.