September typically marks the transition from summer to fall in the Black Hills region of South Dakota, where Mount Rushmore National Memorial is located. Visitors can expect to experience moderate temperatures, crisp air, and fewer crowds than the peak summer months. Daily high temperatures average in the low 70s Fahrenheit (low 20s Celsius), while nighttime lows can dip into the 40s Fahrenheit (single-digit Celsius). This variation necessitates packing layers of clothing to adapt to changing conditions throughout the day. Rainfall is possible, though less frequent than in the spring or early summer.
Understanding the typical climatic conditions during this time allows visitors to prepare adequately for a comfortable and enjoyable experience. Pleasant temperatures make hiking and exploring the surrounding areas more agreeable, while fewer crowds can lead to a more intimate experience with the monument itself. Historically, September has also offered a vibrant display of fall foliage in the surrounding Black Hills, enhancing the scenic beauty of the area. This period offers a balance between pleasant weather and manageable visitor numbers, making it a desirable time for many to visit the memorial.