My girlfriend and I were sitting on the patio of Boulders, a restaurant in Tempe, AZ, eating dinner when we both noticed a series of 7 pulsating orange and red orbs rising from the northern horizon, traveling almost directly south and following single file, somewhere around .5 miles equidistant from one another. As they traveled south, they slowly gained altitude, and passed maybe 1 mile east of us before ascending into the clouds and disappearing. There was a brief pause of perhaps 1 minute, then another series of 7 orbs appeared from the same point on the horizon as the ones before. They followed the exact same path, staying equidistant from one another almost the entire time, until 2 orbs deviated from the path and went east and west just before ascending into the clouds in the same area as the ones before. There was another pause of about 1 minute, before one last orb, pulsating orange and red, rose from the same place, but seemed to go straight upward, then just before reaching cloud cover, it changed direction immediately and began moving southward. It ascended into the clouds in the same place about 1 mile east and just a little south of us that the others had.
All of the objects had a uniform, pulsating orange and red glow. They did not seem to have any distinguishable craft shape, it was like the lights were the entire object or the entire craft was glowing. They all seemed to have an orb shape with no distinguishable features.
There was an older British couple sitting behind us that also noticed the orbs from the beginning. The gentleman initially dismissed them as floating lanterns, but didn't mention that theory after the 2nd series of lights had appeared. After they had all disappeared, he looked at his wife and said, "Well, I think we just saw our first UFO's".
I had seen one of the exact same orbs in the winter of 2012 and had been absolutely befuddled by what I had seen, so I was ecstatic to have had the opportunity to not only see another one, but 15 of them, and also with 3 other people. I filmed the end of both events, although the cell phone video doesn't do the real thing justice (the videos are on my old phone, and I can find them if requested).
Overall, I felt, and the 3 other witnesses felt that there was no readily apparent explanation for what we saw. It/they were clearly not a helicopter, airplane, or blimp, which we see plenty of, due to our proximity to the Phoenix airport. Since the sightings, I've kept my eye on the skies, hoping for a repeat performance, but sadly, there's been nothing. I feel more frustration more than anything, in the sense that I have been unable to find any answers, but I'm grateful I got to see something that has made me ask so many questions.