Israel is a largely arid country, correct? Humid during rainy season, and the subsequent green time, that makes sense. But humid in the summer, when it doesn't rain at all? Yes, definitely confused. Yeah, I understand the confusion. There are very different topographies and weather conditions in our tiny country. Go figure. The coast (Haifa, Tel Aviv, Ashkelon) is muggy in the summer. Right now it's 83 degrees and 57% humidity at 9 am. The temp is going to go up to the high 80s and humidity will stay around 55%. Jerusalem is at an altitude of about 1500' so it's usually about as warm as the coast during the day but humidity is considerably lower and the early mornings and evenings are generally cool, or at least cooler. This time of year even Jerusalem gets humid, when the Nile River peaks (the prevailing winds from the Sahara soak up a lot of moisture over Egypt and bring humidity and clouds our way - but no rain). The south is desert, including the Dead Sea area, so it's usually very dry, but because the Dead Sea is so low, it's awfully hot in summer and quite warm even in winter. In January you can get snow in Jerusalem and it's usually warm enough for a dip in the Dead Sea, an hour's drive away. The Sea of Galilee and surrounding area (with many Christian sites) is also well below sea level, so it's usually warmer than the coast and the mountains, but it's also usually humid. I don't know why but humidity is highest from mid-June to mid-September, our hottest months. We don't get a lot of rain in winter and temps are mild - 40s to 60s - so even if the humidity goes up during/after a rain, it's not uncomfortable. Rainy season is misleading. It's been years and years since we've had prolonged rain (sadly). A rainy day can mean an hour or two of light rain to heavy thunderstorm, and several hours of sunshine as well. It's rare for us to have more than 3 rainy days in a row, and it's (again sadly) normal to have 2 weeks or more with no rain at all. March is about my favorite month when everything is green and there's lots of water flowing in the Jordan River.
Yes, you are absolute right about the holidays. It does happen once in a decade or two that Easter and Passover do not coincide. And the Orthodox (by far the largest Christian population here) Easter is often a week later than the Catholic/Protestant date, once in a while it's a month later. The most frequent occurrence is that Orthodox Palm Sunday (nearly as important as Easter Sunday) and Catholic Easter Sunday are on the same day, and it's during the week of Passover. All three are determined by formulas based on the spring equinox and the phases of the moon. The differences between Orthodox and Catholic are because the Orthodox follow the Julian, not the Gregorian calendar, and that dates back to the "great schism" in the Middle Ages.
Next question? :-)