Esenada weather is considered to be Medeteranian like, with warm sunny days in the (70s F / 20s C) and cool evenings in the 40s-60s...so a light jacket may be needed in the evenings and winter months.
The months of December - March bring the most chance of rain, sometimes heavy, which can cause some flooding of streets. An umbrella may come in handy.
April, May, and June are cloudy in the mornings, but it soon clears up and turns into a warm sunny day with a cool breeze.
Ensenada has some of the best weather you will find anywhere. It has a coastal climate similar to San Diego's with sunny summers cooled by ocean breezes, and mild winters accented with occasional rainfall. Casual or resort wear is accepted at most restaurants and nightclubs, but visitors may want to be prepared to dress more formally for business or special occasions.
Toiletries and Medical Supplies: Virtually anything you need, or forget, may be readily found in Ensenada. Naturally it would be wise to bring your prescriptions medicines, and don't forget the suntan lotion.
Miscellaneous: The U.S. dollar is accepted by almost all businesses except buses, which require pesos. Most large restaurants, stores and hotels accept major credit cards.
Each U.S. or Canadian citizen may return to the U.S. with $400 worth of merchandise duty free, provided it is for personal use. Adults over 21 are allowed one liter of beer, wine or liquor. This duty free exemption is allowed once every 30 days.
Luggage and bags:
Remember to bring your passport if you intend going back to the U.S.A.
Photo Equipment: Buy all the film you'll need, before entering Mexico. It is easy to purchase, but the price is much higher, and sometimes the expire date has passed.
This outdated suggestion will remain, in case there are people left who use film in the digital age.
Luggage and bags:
Pack lightly when traveling to Ensenada, Mexico and take only what is absolutely necessary. First reason: you will need and wear only the bare essentials. Second: you want to eliminate the risk for leaving behind, ruining, or being victim to theft (all of which are likely) for your most adored possessions.
Clothing/Shoes/Weather Gear: LAYERS. your mother would thank me.
Toiletries and Medical Supplies: Ant traps. The ants in Ensenada are DETERMINED to eat your food before you and they outnumber you.
Photo Equipment: Bring a good digital camera. This is true for all trips outside of your bedroom.
Camping/Beach/Outdoor Gear: Towels, flip flops, beach toys
Miscellaneous: Bring your patience. Mexican road trips and general driving in Mexico will test your sanity and make you bite your tongue when the 1987 Honda Civic without a bumper barrels past you. PS. Yelling American traffic laws out the window will not win you any brownie points. Trust me.