LED color temperature can shift slightly over time, typically by 100-300 Kelvin over 50,000 hours, mainly due to phosphor degradation and changes in the LED chip's spectral output. Poor thermal management accelerates this shift, as high junction temperatures break down phosphor compounds faster. Quality fixtures use thermal-resistant phosphors and tight binning (SDCM ≤3 or ≤4) to minimize visible color variation between units and over time. Reputable manufacturers provide color stability data in their LM-80 and TM-21 reports. For projects where uniform color is critical, request fixtures with SDCM ≤3 and verify the rated color maintenance (e.g., color shift within 7-step MacAdam ellipse over lifetime).