I've used a lot of olive oil over the years.  As a foodie, the oil is my sauteing  fat of choice.  I've used expensive, high-quality olive oils and more-economically-priced oils and usually always get good results.

On a recent shopping trip, I encountered something that happens from time to time;  the weather was cold (like it often is in the Twin Ports) and the bottom half of my olive oil solidified in the bottle.  Because this has happened before - and I know my food science - I didn't worry.  But, I wondered if others encounter this and have questions about the occurrence.

All fats solidify at some temperature.  Surprisingly, olive oil sets up at a somewhat higher temperature than you would think: 50-degrees.  As the temperature gets colder, it only becomes more solid  due to the vegetative wax that's inherent in the product. The quality of the olive oil doesn't change and all you have to do to make it a liquid again is bring it to room temperature.

Some people actually use solidification as a test of how "good" the olive oil is - placing it in a refrigerator to see if and how fast it sets up.  However, this test isn't scientific and really doesn't prove anything more than you have an oil that becomes a solid;  it doesn't tell you anything about the quality.

The temperature outside the store the other day was probably in the upper 30's and the wind was pretty strong.  I still plan to use my olive oil without any worry.