Hi, I live about 15 minutes south of DLR.
The weather here right now is pretty cold, rainy and windy.
We were at DLR this past weekend and got rained on pretty badly, even though we made the decision to go based on the weather forecast which showed a 5% chance of precipitation for the rest of the day (Sunday). We were prepared with umbrellas and rain covers for the strollers, but it was miserable, so we left after an hour.
Moral of my story: don't trust the weather forecast. Living so close to the ocean, the weather often has a mind of its own and it's usually EXTREMELY difficult for them to predict, even a few hours ahead, what it will be like.
Come prepared for:
-chilly mornings and evenings (in the upper 40's-mid 50's)
-possible rain, at least on Saturday, and likely Friday, Saturday, AND Sunday
-average daytime temps around 60-65.
-wind...COLD wind
I highly advise HOODED jackets, sweatshirts, etc. When it gets windy here, it feels much colder than it is, and evenings tend to get windy, especially if there is any sort of storm front.
Fireworks will be cancelled if you can look up in the sky and visibly see the clouds moving through the sky. If the clouds are moving by quickly enough for you to discern, it's too windy for fireworks (generally). The reason for this is that Anaheim has a LOT of houses/buildings within close proximity to the park, and the wind could cause the embers from the fireworks to blow over to those structures, creating a fire hazard. If the winds exceed 15mph at the firework level, they will be cancelled. So, it happens very often.
Also of note, Fantasmic WILL be cancelled due to rain, as the rain causes the stage to be dangerously slippery for the performers.