The activity of a Laurentian population of Sorex cinereus cinereus (Kerr) was recorded using the sand transect technique. Data were analyzed to determine the effects of weather on shrew activity. Rainfall increased nocturnal activity but the nature of the relationship was difficult to establish. The time when precipitation started was important in determining the response in activity. The highest activity was recorded when rainfall started in the time interval 1800 to 2400 hours. The onset of precipitation influenced the nocturnal hourly activity. In general, shrew activity increased or decreased as a result of a corresponding increase or decrease in the mean nocturnal temperature from that of the previous night. Nocturnal cloud cover had a significant influence on total daily activity; increased activity was recorded on cloudy nights. Although wind direction did not have a statistically significant influence on activity, in general, higher activity was recorded when nocturnal southerly winds prevailed. Effects of wind speed and duration, barometric pressure, relative humidity, and temperature on activity were not statistically significant.