My initial gut reaction is that you saw a meteor enter the atmosphere pointed right at you. I've see two of these and they freaked me out as that is not the expected normal behavior. That said there is a ton of stuff up there. At my friend's place in the country it is not uncommon to see upwards of two dozen satellites of various brightness if we are up for several hours. Being that bright, 10+ time brighter than Venus currently, I'd second guess that it could have been a plane/helicopter at a distance from the observer; usually lower in altitude with an inversion layer at the point of the light. What was the weather like? clear skies? Upper level clouds? Oh I got your weather, and it does not look like an inversion layer echo. How long are we talking about? Seconds? Minutes?
The weather was crystal clear. I have quiet good skies here, and I would say I can see any satellite with a brightness below 5 without having to spend 2 hours getting used to darkness. At first I thought it was Sirius, but then it starting getting brighter and Sirius is never that bright, and Venus doesn't rise from that part of the sky. We are talking of a magnitude -7 for over a minute, like wait a minute, this thing is so bright and for so long that perhaps I have time to go pick my camera and take a picture. It was a satellite because when it starting dimming it was just a tiny magnitude 3 dot until I couldn't see it anymore and it seemed to be moving then. What surprised me the most was the length of the flare and that it seemed stationary. Second thing that surprised me was that I thought it was an iridium flare but when I went to look at it on heavens above there wasn't any object with that brightness. Could have been an airplane, no helicopters at night, since I'm relatively near Barcelona airport and there are several airways over my place, but I am 99% sure it wasn't an airplane.
Well you definitely described a flare of something that looks like a satellite. I wonder if the new Galileo stuff flares like the Iridium, and if so are they in the databases yet? Iridium flares can get to -7.8 or so if you are dead center on the flare path; the brightest I usually see are about -5 or so, just about twice as bright as Venus.