National City, CA Noise Ordinances: Decibel Limits (2026)

Title 12 of the National City Municipal Code is the Noise Control Ordinance. Section 12.06.020(D) bars any person from operating a source of sound, or allowing noise on property they own, lease, occupy or control, that exceeds the environmental or nuisance noise level of Table III at any point on or beyond the boundary of the property where the sound is produced.

Table III sets the allowable level in dB(A) for two periods, 10 p.m. to 7 a.m. and 7 a.m. to 10 p.m. All residential land with fewer than 9 dwelling units is limited to 45 and 55. Multi-unit residential of 9 dwelling units or more, plus public space, is limited to 50 and 60. Commercial is 60 and 65. Light industry, defined as industry east of I-5, is 70 at all hours, and heavy industry, industry west of I-5, is 80 at all hours. Where two or more dissimilar uses share a property, the more restrictive limits apply.

There are two measures. Environmental noise is the A-weighted equivalent sound level for any hour, Leq(h). Nuisance noise is a level not to be exceeded at any time, with no hourly averaging. Under Section 12.06.040, a noise that contains a steady whine, screech or hum, a repetitive impulsive noise such as hammering or riveting, or music or speech has the Table III limit reduced by five dB. If the measured ambient level already exceeds the table, the ambient level becomes the standard. Chapter 12.08 sets separate interior limits for multifamily units with a shared wall.

Code enforcement officers investigate complaints, using a sound level meter whenever practicable with the A weighting scale and slow response, the microphone four to five feet above the ground and at least ten feet from the source. The planning director enforces environmental noise and the chief of police enforces nuisance noise, and Section 12.06.020(E) says failure to take a measurement does not bar enforcement.