Rochester/Paleozoic Plateau Upland

September 2026 brought 7.7 inches of precipitation to Houston County, 3.9 inches above the normal of 3.8 inches, ranking as the 9th wettest September in the county's 132-year record. This exceptional rainfall followed early-September drought conditions that affected 91.86% of the county but have since cleared entirely.

Houston County entered October 2026 with no drought classification for the first time since early September, when abnormal dryness covered 91.86% of the county. The return to normal conditions reflects the exceptional September rainfall that saturated the soil and recharged water supplies.

A monarch was observed on 2026-10-11 in Decorah, Iowa, consistent with the fall migration through the Upper Midwest. In Minnesota, monarchs peak in migration around August 23 and thin substantially by October 18. The October observation falls in the active migration window for this region, with butterflies still on their southbound journey toward central Mexico overwintering sites.

Multiple state and federally threatened plant species have documented ranges overlapping the Rochester area, including clasping milkweed and cream wild-indigo, both recorded in the region in September. These species require specialized prairie and dry habitat conditions that are increasingly rare in the Midwest.

Japanese silver grass was recorded at Church Road in Spring Grove on 2026-10-04. This introduced perennial grass spreads via rhizomes and can form dense stands that displace native vegetation in disturbed areas.

Velvetleaf was recorded at Beaver Creek Valley State Park on 2026-10-07. This annual weed native to South Asia is considered a damaging invasive in Midwest agricultural areas, particularly for corn and soybean crops, and can reduce crop yields by up to 34% if not controlled.