Grenadilla wood is one of the most beautiful, durable, and stable products of nature: hard, dense, and extremely close-grained. It is also one of the most expensive ones and since 2016 listed as endangered by the Washington based Cites organization.
The wood used for woodwind instruments is between 80 and 300 years old. Chances are high, that your instrument's material started to grow when Beethoven was alive. Since then it has been exposed to severe storms, monsoon rain, heat, and wind. Only wood that made it without damages are used for good instruments.
Acoustically, it is an ideal material, imparting its flexibility to the tonal characteristics of the clarinet which sensitive musicians consider essential to artistic expression.
One of the biggest and most destructive forces that can damage wood is moisture. Wood will always try to absorb as much moisture and humidity as it can. This causes the wood to expand, allowing moisture to enter the cells. This can cause tension within the wood, resulting in cracks, warp, or mold.
The temperature only has an indirect influence. Higher air temperatures are able to store more moisture. But if there is no moisture available, like in the desert, wood will dry out quickly and shrink. Since this process will not occur evenly through the entire piece of wood, cracks are often the result.
Dry air- in any form or temperature- is another big danger for woodwind instruments.