San Bernardino County Decibel Limits Rules (2026) — What You Need to Know

San Bernardino County's decibel-based noise standards are established in Table 83-2 of Development Code Section 83.01.080. The system is designed around the concept of "noise-impacted areas" — zones where existing or projected noise levels exceed the standards set for the receiving land use.

The tiered duration system works as follows: the base noise standard for the receiving land use cannot be exceeded for a cumulative period of more than 30 minutes in any hour. The standard plus 5 dB(A) cannot be exceeded for more than 15 minutes. The standard plus 10 dB(A) cannot be exceeded for more than 5 minutes. The standard plus 15 dB(A) cannot be exceeded for more than 1 minute. And the standard plus 20 dB(A) cannot be exceeded for any period of time.

For residential zones, the base standard is 55 dB(A) during daytime hours (7 AM to 10 PM) and 45 dB(A) at night (10 PM to 7 AM). This means that during nighttime hours, any noise exceeding 65 dB(A) at a residential property line — even momentarily — constitutes a violation. The interior noise standard caps the average of the maximum intrusive sound levels at 65 dB(A) over a 24-hour period.

Special adjustments apply in certain situations. If the ambient noise level already exceeds the tabulated standards, the allowable level is raised to match ambient conditions. Conversely, noise consisting entirely of impact sounds (like hammering) or simple tones (like alarms or beeping) must meet standards reduced by 5 dB(A), reflecting the greater annoyance these types of sounds cause. All measurements must use ANSI-standard Type 1 or Type 2 sound level meters on the A-weighted scale.