Executive Summary: The Climate Impact Company month 1-4 outlook valid for March through June 2024 is updated. The forecast is based primarily on deceleration of an El Nino climate to neutral ENSO over the next 2-4 months. Forecast highlights include a warmer than normal spring for the North and Northeast U.S. while the Southwest is cooler than normal. The Southwest cool forecast is made with below average confidence as a warmer solution is possible. The precipitation forecast features a wet spring in California and the western Great Plains with a dry bias for much of the Interior East. Climate discussion: Climate forecasts are generated by historical relationships (of climate) to the ENSO regime and most recently the tendency for warming SSTA in the mid-latitude oceans. The MAR-JUN 2024 Climate Impact Company constructed analog (CIC-CA) forecast is based mostly on deceleration of an El Nino climate into neutral ENSO by mid-year. Usually, equal consideration is applied by the mid-latitude ocean SSTA regime. However, conditions across the northeast Pacific are quite different from the 10-year climatology which has featured warming in this region. The warming generally leads to a western North America ridge pattern. The long-standing marine heat wave in the Northeast Pacific has shifted west of the Dateline leaving the northeast Pacific without the anomalous warmth common within the optimal climate normal (OCN). In the North Atlantic, waters have cooler across the western basin while historical warmth persists in the tropics and eastern basin. Applying this relatively unique mid-latitude SSTA pattern to the spring 2024 forecast is difficult (now). Consequently, the ENSO bias is heavily weighted to generate the outlooks. The North Atlantic is likely to warm, and that projection, is considered in the outlook. However, forecast models are warming the Northeast Pacific rapidly and that warming is not appearing yet. As summer 2024 nears, increased input on climate forecasts based on mid-latitude SSTA patterns will increase. For now, the outlook is mainly an ENSO-based constructed analog. Fig. 1-2: The Climate Impact Company meteorological spring 2024 temperature and precipitation anomaly outlook. March 2024 outlook: A prohibitively warm first half of March for the North and East U.S. is indicated by dynamic models. ECMWF “weeklies” indicate the back half of March is cooler, especially across the South U.S. The average of the 2 scenarios is indicated in the CIC-CA climate forecast for March: Warm Northeast and cool South. Springtime climate forecasts historically have the least skill, especially precipitation outlooks. The CIC-CA forecast is wetter than normal across much of the U.S. The most confident (wet) forecast is across California and Florida. Least confident is the wet anomaly in the Midwest U.S. where (recently) soils are drying, the dry forecast in the Southern Appalachians which may be displaced farther west, and the marginally wet prediction in Texas where drought is starting to redevelop. Fig. 3-4: The Climate Impact Company March 2024 temperature and precipitation anomaly outlook. April 2024 outlook: The mid-spring outlook is a relatively straight-forward decelerating El Nino climate forecast. Lingering high latitude warmth is indicated while the Southwest U.S. is cool-biased due to a persistent upper trough. The Southwest U.S. trough spawns a wet pattern featuring severe thunderstorms across the Great Plains. However, the eastern 40% of the U.S. averages drier than normal. California is wet (again). Warmest anomalies are centered on the Upper Midwest into the Canadian Prairies. Fig. 5-6: The Climate Impact Company April 2024 temperature and precipitation anomaly outlook. May 2024 outlook: The late spring forecast is dependent on presence of cool phase Pacific decadal oscillation (-PDO) and warm phase Atlantic multi-decadal oscillation (+AMO). The +AMO is confidently forecast while -PDO is uncertain. Consequently, the cool Southwest U.S. forecast is least confident and the warmth across the East U.S. is a reliable projection. The precipitation pattern favors wet weather in the Mid-Atlantic States while the Mid-south and parts of the Midwest are dry. A low confidence wet climate forecast is indicated across much of the West and Northwest U.S. Fig. 7-8: The Climate Impact Company May 2024 temperature and precipitation anomaly outlook. June 2024 outlook: As summer 2024 arrives, ENSO is neutral. Favored, is presence of -PDO and +AMO. The climate (forecast) result is hot across the southeast quarter of the U.S. with heat spreading north to the Ohio Valley and Mid-Atlantic States. The anomalous heat will accelerate drying of soils across the Southeast U.S. and Gulf States. A strong thunderstorm pattern is indicated for the Midwest States. Once again, the cool bias in the West is the least confident part of the forecast where a warmer/drier solution is possible. Fig. 9-10: The Climate Impact Company June 2024 temperature and precipitation anomaly outlook.