It's 105 degrees in texas... aluminum radiator?

[Mr 5 0]

If it heated up slowly while in traffic than you probably need a new clutch/fan.

They only work at idle and low rpm's so if the clutch fluid has leaked and it's running sluggish you'll slowly heat up while sitting in traffic on a real hot day.

Other items to consider:

A 20/80 water/antifreeze mix is recommended and of course a check of the entire cooling system may be in order. Replace the radiator cap if it's more than a few years old and do a flush and refill if you haven't done so recently.