Short-term temperature and precipitation patterns associated with firearm discharge incidents in Detroit, MI, USA...

Firearm violence is a leading cause of injury and death in U.S. cities. Weather may shape firearm discharge risk by altering outdoor activity and social contact, yet evidence on lagged effects and on the relative importance of daytime versus nighttime temperatures is limited. This research tests lag-associations of precipitation and temperature with firearm-related incidents in Detroit, Michigan.

We studied firearm discharge incidents in Detroit, Michigan from 2021 to 2025 using police records with geocoded locations. We paired incident dates and matched control dates using a time-stratified case-crossover design and assigned daily precipitation and maximum/minimum temperature for the incident day and for each of the prior 7 days. We estimated exposure-lag associations using distributed lag non-linear models and evaluated whether neighborhood ecological characteristics modified weather effects.

Among 4062 firearm discharge incidents between 2021 and 2025, higher temperatures were associated with increased odds of incidents in cumulative models. Associations with minimum temperature remained elevated across lag windows up to 7 days. Cumulative exposure to precipitation at the upper end of the distribution (95th percentile = 0.54 inches (13.7 mm)) was associated with reduced odds of gunfire incidents over short accumulation windows (0-1 days and 0-3 days), with attenuation and imprecision when cumulated through 7 days. Weather associations were generally consistent across neighborhood characteristics.

In this urban setting, warmer conditions, especially warmer nights, were associated with higher odds of firearm discharge incidents, while higher precipitation was associated with lower odds of incidents over short lag windows. These patterns suggest that weather-sensitive opportunity structures may be important for anticipating short-term risk periods.