Heat is important. We tend to think of plant survival in terms of cold survivability. Heat can matter, too. Some plants can't take the heat. This may not be as obvious as is the factor of cold survivability.
Most plants can tough out high temperatures.
They may not flourish, but they survive. A few may perish from the heat, but most will live through it, though they may be weakened. The most common examples are the cool-season grasses. Kentucky bluegrass is one of these. In much of the US, this common lawn grass grows well in the spring and fall, but not as well in the summer.