Low Temperature Limit for Puck and MDBT42Q

Yes, there are! You have:

• 'Lithium Manganese Dioxide' - these are the same chemistry as the CR2032 so are 3v but you can get them as AA (or 1/2 AA, which is quite neat). This AA cell is 2000mAh (so about 10x the capacity of the CR2032): http://uk.farnell.com/varta/6117101301/b­attery-lithium-cr-aa/dp/8636192
  
• LiFePO4 batteries are rechargable but could also be an option - the operating voltage is pretty much spot on
  
• 'Lithium Thionyl Chloride' - these are the ones you get in long life smoke alarms and stuff like that. They go down to -50°C and have slightly more capacity than the Lithium Manganese Dioxide batteries. The only gotcha is that when fully charged at room temperature they're basically 3.7v.
  
  
  

If you look at the nRF52832 datasheet, the recommended operating voltage maxes out at 3.6v. However the absolute maximum voltage is 3.9v.

Nordic says:

Maximum ratings are the extreme limits to which the chip can be exposed for a limited amount of time without permanently damaging it. Exposure to absolute maximum ratings for prolonged periods of time may affect the reliability of the device.

So, it's on you - but if it were me I'd say that 3.68v from a Lithium Thionyl Chloride battery is probably close enough to 3.6v (given the 3.9v maximum) that it's not going to cause you any problems. Especially as at -20 the voltage does drop to 3.6v when fully charged :)