Stream chemistry in permafrost watersheds is highly seasonal due to ground thaw and declining streamflow after spring melt, reducing hydrologic connectivity with organic-rich flow paths in fall. We quantified the magnitude of stream chemistry seasonality (driven by processes other than seasonal streamflow) across 10 watersheds. Watersheds with steeper slopes saw a more rapid decline in DOC (dissolved organic carbon) concentrations, while greater permafrost extent led to a greater relative increase in ion concentrations.