AbstractIntroductionSnoring and sleep‐disordered breathing (SDB) are frequent pediatric conditions. Although allergies and respiratory viruses have been pathophysiologically implicated in these conditions, their seasonal distribution has not been examined.MethodsThe records of all children participating in a prospective, cross‐sectional community‐based research study that included a questionnaire on snoring frequency and loudness and an overnight sleep study were retrospectively assessed for seasonal patterns based on the day the children were evaluated.ResultsA total of 1,051 children were included with a mean age of 7 years. There were no seasonal differences in the number of children evaluated or in their demographic characteristics. However, the odds of increased snoring frequency and loudness were significantly higher in spring and summer and lowest in fall (P < 0.001). However, the mean AHI was highest and the nadir SaO2 was lowest in winter and spring compared to summer and fall (P < 0.001 and P < 0.03, respectively).ConclusionSnoring and the severity of SDB exhibit distinct and essentially non‐overlapping patterns of seasonal variation, with peaks in spring–summer for snoring and peaks in winter‐spring for SDB severity. These findings suggest that both seasonal viral and allergen burdens may contribute to SDB severity and may prompt differing clinical referral patterns throughout the year. Pediatr. Pulmonol. 2011; 46:581–586. © 2011 Wiley‐Liss, Inc.