No, but they are less efficient over about 25C. If you have solar panels though you don't care too much about their efficiency, you care about how much energy you get out of them. You'll get the most energy on long summer days.
On 13 June 2023 the Telegraph reported that 'Britain fires up coal plant as weather becomes too hot for solar panels to work efficiently'. This was picked up (ironically) by the Sun, by pundits Andrew Neill and Toby Young, and tweeted by a DUP MP. The gory details are well-described in Private Eye (No. 1601, p11). The assertion was rebutted by the trade association Solar Energy UK: Solar power works best in summer.
Originally posted as a FAQ.