Do cats get anxious because of the heat?

Absolutely! Cats fear the heat more than we do. When the outside temperature rises, cats tend to become exhausted due to hyperventilation. As a result, they feel lethargic and lose their appetite.
Cats’ thermal regulation differs from that of humans
Unlike humans, who rely mainly on perspiration to regulate body temperature, cats have a different mechanism. They don’t sweat like we do, with the exception of a few sweat glands on their paw pads. The small amount of sweat they produce is not enough to effectively regulate their internal temperature, especially during intense heat waves. It takes about a week for cats to adapt to sudden temperature changes, so the heat of early summer can be a challenge for them.
Other ways for cats to cope with rising temperatures

When confronted with a sudden rise in temperature, cats use other methods to combat the heat:
Increased respiratory rate: Cats breathe faster, which facilitates the evaporation of water from their bodies, helping them to cool down.

