Siwa sää — joulukuu

December is the winter season here and the boards treat it as the right time to come - the springs, the cycling, the desert itself - with one caution repeated every time, about the nights. Out in the desert the temperature can fall to about 5C after dark, and anyone camping wants blankets, a light down jacket and socks rather than a fleece. Our row sits close to that: 10.1C at night reading as 7C in a 17.9 kph wind, against 19.9C by day reading as 17C. Rain is 2.5mm across not quite one day. The middle of the day is genuinely pleasant, though a light jacket earns its place in the shade. The record: humidity 68 percent, 9.1 hours of sun and AQI 72.

Regulars are specific this falls squarely within the region's own October-through-April best window, daytime temperatures rarely climbing past the low 20s Celsius, the sun still fierce despite a cold wind that can pick up. Our row backs that mild, genuinely dry read, 18.2C over 8.5C nights feeling 6C, with rain essentially absent, 2.7mm across less than a day, and humidity at 64 percent. Regulars are consistent this counts as the coldest month of the year here, warm enough by day but genuinely bone-chilling cold once the sun goes down, real layers for the night the standard advice regardless of how mild the afternoon felt. The record: 9.1 hours of sun, a 20.2 kph wind and AQI 50.

October to April is the recommended window for this corner of the desert, described as warm but not boiling by day and cool at night and early morning - and February sits at the cold end of it. One traveller's memory of arriving here at dawn in a jeans jacket is the useful detail; our row gives 8.7C nights that feel like 6C, and afternoons of only 19.1C that feel like 16C, because a 19.6 kph wind runs across open ground with nothing to slow it. Anyone sleeping out needs more bedding than a desert suggests. Rain is essentially nil, 1.5mm in the month. The record: humidity 57 percent, a dew point of 5.5C, 9.9 hours of sun and AQI 56.

October to April is the window regulars give for Siwa, which makes April the last of it before the Western Desert summer takes over. Their description of the end of that season - cool at night and in the early morning, sunny and warm without being boiling by day - is our row exactly: 28.3C falling to 15.4C, a thirteen-degree swing at under 40 percent humidity, so the afternoon actually reads cooler than the thermometer at 26C. Rain is 0.4mm across a tenth of a day. The one hazard they mention is wind-borne rather than wet: sandstorms happen, and our 22.7 kph average is the machinery for them. The springs and salt lakes are the reason to be here. The record: 11.5 hours of sun, 12.9 hours of daylight and AQI 66.

October to April is the window the Siwa forum recommends, and a late-March trip report describes exactly the shape of it: cool nights and early mornings, days sunny and warm without being punishing. That matters here because almost everything is outdoors and exposed - the Shali fortress, the Mountain of the Dead, the Oracle temple, the dunes of the Great Sand Sea, the salt lakes. The springs are the other draw, Cleopatra's for the setting and Bir Wahed out in the sand for the warm one. Getting there is a long desert bus ride from Cairo or Alexandria with several military checkpoints and occasional luggage inspections, described as polite. The record: 23.1C days, 11.8C nights, humidity 48 percent, half a precipitation day, 10.6 hours of sun and a 23 kph wind.