 meaning the sky has become cloudy and does not rain. its skin is peeling off. by skin he meant the clouds and by peeling off he meant that it is dispelling as if it is peeling off.
يعنى السماء أضحت محولا لا تمطر جلدها يتوسف أراد بالجلد، السحاب؛ وبالتوسف أنه ينقشع فكأنه يتقشر.