Our study has found that there is no correlation between the absolute number of patients with active SLE and the mean humidity, while there is an inverse correlation between the number of patients with active SLE and the mean temperature, demonstrating that, based on genetic background, a low-temperature environment may be one of the causes to induce SLE. Some scholars speculate that a high incidence of SLE in winter may be caused by UV accumulation after exposure to strong sunlight in summer. 11 Leone et al. 18 found that the level of serum anti-dsDNA is increased, while the levels of C3 and C4 are decreased in patients with SLE from August to January. The mechanism of a high incidence of active SLE in winter and a low incidence in summer remains to be further elucidated.