In Cairo, and along the Nile River Valley, the climate is a desert climate (BWh according to the Köppen climate classification system), but often with high humidity due to the river valley's effects. Wind storms can be frequent, bringing Saharan dust into the city during the months of March and April. High temperatures in winter range from 19 °C (66 °F) to 29 °C (84 °F), while night-time lows drop to below 11 °C (52 °F), often to 5 °C (41 °F). In summer, the highs rarely surpass 40 °C (104 °F), and lows drop to about 20 °C (68 °F). Rainfall is sparse, but sudden showers do cause harsh flooding. In New Cairo, a place of higher elevation than Downtown Cairo, the temperatures often drop below zero during winter causing morning frost
