Weather indices significantly affecting movements, affective, and behavioral states remain largely unknown among children with profound or severe intellectual and multiple disabilities (PIMD/IDs). Main, seasonal interaction and 24-hour time-offsets effects of outdoor weather indices on the movements and behaviors of children with PIMD/IDs were explored using hierarchical and general linear models. Caregiver-interpreted facial, body, and limb movements and behaviors of 20 8-to 16-year-old children with PIMD/IDs and simultaneous online-API-and-sensor-collected app-based weather, proximity and time data were collected in 105 single-dyad video-recorded (30-hour) natural-child-caregiver-dyadic interactions over 5 months. Fluctuations in outdoor atmospheric pressure, humidity, cloudiness, wind speed, season, daylength, time (12 to 1 pm), and conditions were predictive of variations in movements and behaviors, which in turn, also responded to increased indoor UV, humidity, and cloudiness levels during winter, and increasing atmospheric pressure and decreasing humidity during fall. While outdoor temperature, atmospheric pressure, humidity, and cloudiness immediately affected variations in movement and behavior outcomes, time-offset wind-related indices had significant delayed effects at several time lags. Evidently, variations in movements and behaviors of children with PIMD/IDs are affected by seasonal variations and current or delayed fluctuating levels of outdoor weather indices which has significant implications for communication and educational interventions.