Weather wizards (1939)

Modern meteorology and a hard-working government weather team put their science and organization to work as a cold front moves from Alaska toward the citrus groves of Southern California. First, the scientists predict the storm's course, giving several days' warning to farmers and growers. The growers, typified by the Morgan family, prepare the oil-burning pots throughout their grove. Then, as the temperature dips below freezing, they light the pots. The cold snap continues as oil-supplies dwindle; the smoky air slows traffic, including trucks bringing more oil. The scientists strive to predict how long freezing temperatures will last: can the Morgans hold out?