High Temperature on 6248 Stack

Hi,

We have been experiencing high temperature issues on Stack  of three switches. 

The show system outputs are shown below

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-switch#show system
System Description: Dell Ethernet Switch
System Up Time: 740 days, 00h:37m:00s
System Contact:
System Name:ABC-switch
System Location:
Burned In MAC Address: A4BA.DB5D.0CFE
System Object ID: 1.3.6.1.4.1.674.10895.3011
System Model ID: PCT6248
Machine Type: PowerConnect 6248
Temperature Sensors:

Unit Temperature (Celsius) Status
---- --------------------- ------
1 37 OK
2 40 OK
3 46 Not OK

Line 1394: <189> JUN 13 21:32:00  TRAPMGR[214101568]: traputil.c(906) 46499 %% Temperature of unit 3 has exceeded the device specific limit

Line 51: <189> AUG 03 22:19:42  TRAPMGR[214101568]: traputil.c(906) 83038 %% Temperature of unit 3 has exceeded the device specific limit

show process cpu

Kernel/Interrupt/Idle 94.20%
Total 100.00%

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What possible reasons can be there for intermittent high temperatures?

As the max operational temperature is 45, what max temperature the dell switches can work without any performance issues?