Is this temperature safe?

Yes, thats high! I would suspect you have one or more problems here within the cooling system:

• The system is dusty and/or heat sink fins are clogged with dust
• Fan is bad or the blades are dirty
• The heatsink has lost its fluid, needs to be replaced
• The thermal paste is old, bad or not put on correctly

I would recommend a better app here to monitor things: TG Pro. The full version offers a very good diagnoses function and gives a more discreet view of the sensors and fans. It's our standard app for our systems.

Of course you could still visit an Apple Store ;-}