rodman99999 may be technically right on the actual melting point of solder. However, he failed to include the fact that all mass is essentially a "heat sink". This means that if your solder tip is at 216 C, it could very well be melting the WBT solder "at the tip of the soldering iron". BUT the rest of the solder mass is rapidly cooling because the board traces and the board itself is soaking up all that extra heat. This means that you will really never fully melt the solder point if you use such a low temperature. Oh, it may eventually melt if you sit there for about 30-60 seconds waiting for the rest of the solder point and trace to heat up enough to melt everything, but this is not the right way to solder components. You want to heat the solder fast enough to melt and join/dis-join without excessively heating the component part (capacitor / resistor / etc.).
This challenge is compounded by the fact that on many boards during the original manufacturing process, the solder has actually flowed through the hole to the other side of the board and may be still "holding on to the component" even though you have melted the main solder point on top of the board. This means that you actually have to crank up the heat enough so that it melts the solder all the way through the hole to the other side (without too much heat that can lift the traces off the board). It's somewhat of an art form.
All my advice has come from 15+ years experience of doing large amounts of electronic equipment rebuilds and soldering/de-soldering.
One of the reasons I recommend the 60-75 watt stations is that you need enough current to keep the solder tip hot, because as soon as you use the tip to melt the solder, the tip itself starts to cool down. I use a high end Hakko FX-951 station. This has a soldering iron where the heating element is actually part of the tip (that looks like a pencil by itself). Since the heating element is right at the tip, it is very effective at keeping the temperature constant -- the station can monitor tip temp and vary the current to keep the temp at a constant point. This station and tips are much more expensive than your $50-100 budget stations, but it works a lot better. The cheaper stations have a heating element at the base and the tip is just a solid piece of metal. The station doesn't actually know what the temp at the tip is. It just continually provides current to the heating element.
I recommended 350 C as a starting point because I have never been able to melt solder under this temp. I have never seen board traces lift at this temp either. You will find that on many manufactured boards, it can be difficult to heat the solder enough to pull out the component part.
Also, if you use a tiny tip (like a 1mm or 1.6mm chisel tip), you will need to crank up the heat even more because the tip does not have enough mass and it loses temperature faster. If you use a large tip, then it has a lot more heat mass and you need to be careful on the temp.
My main tips are a 1.6mm chisel and a 2.4mm chisel. I mostly use the 2.4mm, but I will grab the 1.6mm if I'm doing a small part with thin wire leads. Many times, the 1.6mm just does not have enough heat mass to effectively solder the component, even at a 399 C temp.
At 350 C you are pretty safe. I have seen board traces lift when using 399 C with larger tips (such as my 2.4mm chisel or larger). These are boards where the traces are all on one side and very thin (and the hole do not have through-hole barrels). Essentially, the only thing holding onto the component leads are the thin trace pads on one side.
Don't use the tiny pencil tips. I have never been able to successfully solder with them. They are just too tiny. A 1.6mm chisel is the smallest I have used consistently.
