There are some good hints.
On one hand, lower temperatures are better for capacitors. In their capacitor datasheets, Vishay supplies a chart indicating by how much expected lifetime is increased as a function of temperature and ripple current. The increase is of multiple orders of magnitude.
Here is an example for 013 RLC series, I think the worst of all (Fig. 10, p. 4):

Similar for TDK B41858 (p. 14):

Generally aluminium electrolytic capacitors are all rated down to -55°C to -40°C. All bear the IEC 60068 climate category 40 or 55 too.
But it also seems that the higher voltage capacitors have much shorter range. For 150 CRZ (250 CRZ-V for high vibration) the rating goes from -55°C to -40°C after crossing 63 V. The 056 PSM-SI snap-in are -40°C, but their 200–450V counterpart (057 PSM-SI) is only -25°C. Similar TDK’s B43858 series, which are rated for -25 °C.
In Vishay’s outline of their test procedures, for cold endurance testing with no voltage, the requirements include “no leakage of electrolyte.” Which would also suggest that one of failure modes in low temperatures is an electrolyte leak.
I have no idea, what mechanism would be responsible for either.
Since the subject was brought up, a safety reminder.
- If possible, don’t store harmful substances in what may be confused with a food container.
- Label, label, label. Label everything. And remove/cover any labels that may suggest different contents.
- Keep away from creatures, human and non-human, that may have limited capacity to understand their actions. Most notably that means kids, but also yourself being drunk or experiencing low glucose.