Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Wiping over socks in wudu both in summer and winter.
Answering your question, the late Saudi scholar, Sheikh Ibn Baz (may Allah have mercy on him) stated:
The general meaning of the sound hadiths indicates that wiping over socks or leather slippers in wudu is permissible both in winter or summer.
I do not know of any evidence to indicate that this is only permitted in the winter, but it is not permissible for anyone to wipe over his socks etc. unless the conditions set out by Shari`ah are met.
These conditions are as follows: the socks must cover the part that is washed during wudu; the socks must be put on when one has wudu, and attention must be paid to the length of time for which that is permitted.
The duration for wiping over the socks is one day and one night for one who is not traveling, and three days and nights for the traveler, starting from the first time one wipes over them after breaking one’s wudu according to the more correct of the two scholarly opinions. (Majmu Fatawa Wa Maqalat Mutanawwi`ah Li Samahat Al-Shaykh Ibn Baz, 10/113)
Almighty Allah knows best.
Source: www.islmaqa.info