Climate at Ista Weyr

"Ista's climate is strikingly different than that of Igen. Like Nerat, Ista has rainforest, not desert. A narrow transition zone in northern Ista and southwestern Igen grades between two vegetative extremes. Ista has more precipitation, due to its marine location, and is further south than much of Igen. Again, the contrast is an example of the richly striking variations in Pern." ~ Atlas of Pern, p. 11.

Ista Island is located on the Western Stream Current, which is heated by the equator and brings warm wet wind towards Ista, making it even more tropical than its latitude might otherwise allow. The Western Stream Current shifts to the south seasonally, giving Ista a slightly dryer winter, as more of the rain misses the island, though the average temperature rarely varies far from 80 F (26.7 C)

While most of the Northern Continent heads into winter, Ista Island begins its dry season. Perhaps that should be 'less wet' season since the island is never more than a few days from a shower of some sort. Most mornings start out clear, humid and breezy but mid-afternoon sees a brief shower two or three times a week. The skies have usually cleared by the evening. There is very little temperature difference at night and over the course of the season, only a few nights will get so cool as 70 F (21.1 C). The dry season lasts through winter and spring.

Towards the end of spring the Western Stream Current again aims towards Ista and along with it comes excessive moisture and much more turbulent weather. Morning often start out with a haze that burns off as the sun climbs into the sky. Mid afternoons are marked by a daily downpour or thunderstorm that drenches everything. The sun may come out again, but this part of the day is oppressively humid and most people are thankful for those stiff ocean winds that make the late afternoons more bearable. It is during this season that the island may reach its peak temperatures, nearing 90 F (32.2 C). Though the skies may clear in time for a sunset, the coming night brings little relief from the heat as the high humidity acts to further stabilize the temperatures.

The wet season is also marked by a number of severe tropical storms. Disturbances created by the contrasting Western Stream Current and the Great South Current often grow as they leave southern-most tip of Boll and travel east towards Ista. Tropical waves, depressions and storms are relatively frequent during the summer and autumn. The rare hurricane may develop, but few of them hit Ista and instead they often they pass to the south, drawing moisture away from the island and giving it a brief respite from the regular rain showers.