Executive Summary: The Climate Impact Company month 1-3 ahead climate outlook is updated. The outlook emphasizes wet weather across Southeast/East-central Brazil for the first half of Q4/2023 followed by widening dry climate most focused on Central Brazil while the wet pattern backs into Northeast Argentina later during Q4/2023. Heading into summer, the primary concern is flooding rains in Southeast Brazil with the opposite regime, a drought, widening and intensifying in Central Brazil. Methodology: The Climate Impact Company month 1-3 ahead climate forecast is valid for OCT/NOV/DEC 2023. The constructed analog forecast is based on climate correlation with regional SSTA patterns influential to South America climate. The regions of influence considered for this forecast are ENSO, the marine heat waves east of Argentina and near and east of New Zealand, the Amundsen Sea cool pool southwest of South America, tropical South Atlantic (TSA) index, and the Indian Ocean dipole (IOD). Also heavily considered for the Q4/2023 forecast is anomalous soil moisture and trend. Climate: During the past month, the prevailing upper air pattern across South America has featured a vigorous upper trough across the southern continent and weak ridge across northern Brazil. Due to seasonality and oncoming El Nino, the prevailing upper air pattern for Q4 of 2023 is a split in the upper trough with weaker troughs either side of Argentina and the upper ridge pattern across Brazil amplifying. Consequently, the sensible weather for Q4 of 2023 features a hotter regime for Brazil with marginally cool conditions lingering in Argentina. The rainfall forecast is linked to an El Nino climate and projects vigorous rains across Southeast Brazil while Central Brazil is very dry. Wet weather also develops on the north-central South America Coast. The primary drivers of the Q4 2023 outlook is a strengthening El Nino climate which is causal of wet Southeast Brazil/dry Central Brazil climate while a warming tropical South Atlantic is the catalyst for a wetter regime on the North Coast. Fig. 1-2: Climate Impact Company OCT/NOV/DEC 2023 constructed analog temperature and precipitation anomaly forecast for South America. October 2023: The mid-spring outlook is adjusted wetter in Southeast/East-central Brazil and therefore not as warm as previously indicated in this sector. The very warm-to-hot pattern is across the north and west portion of Brazil where mostly dry conditions are likely. Argentina is adjusted drier and cooler than normal. Fig. 3-4: Climate Impact Company October 2023 constructed analog temperature and precipitation anomaly forecast for South America. November 2023: Brazil is hotter than normal to finish meteorological spring. The forecast is slightly less hot for Southeast Brazil compared to the previous outlook. In Argentina, the outlook is adjusted warmer to near normal temperature. The wet pattern in Southeast Brazil persists while to the north the remainder of Brazil is turning drier. Wet weather develops on the North Coast of South America, a forecast change. Drought concerns in Central Brazil increase while flooding rains are an issue in Southeast Brazil. Fig. 5-6: Climate Impact Company November 2023 constructed analog temperature and precipitation anomaly forecast for South America. December 2023: Early meteorological summer brings drought concerns in Central Brazil where a dry and hot climate pattern persists. Wet weather continues in Southeast Brazil to Northeast Argentina. Flooding concerns persist in Southeast Asia and the Northeast Argentina drought is eroding due to early summer rains. Fig. 7-8: Climate Impact Company December 2023 constructed analog temperature and precipitation anomaly forecast for South America.