Rain And Forgiveness

The Gemorah Taanis (7b) says אָמַר רַבִּי תַּנְחוּם בַּר חֲנִילַאי אֵין הַגְּשָׁמִים יוֹרְדִים אֶלָּא אִם כֵּן נִמְחֲלוּ עֲוֹנוֹתֵיהֶן שֶׁל יִשְׂרָאֵל שֶׁנֶּאֱמַר רָצִיתָ ה׳ אַרְצֶךָ שַׁבְתָּ שְׁבִית יַעֲקֹב נָשָׂאתָ עֲוֹן עַמֶּךָ כִּסִּיתָ כׇל חַטָּאתָם סֶלָה.  The Sfas Emes notes that may be why we are judged about  rain right after Yom Kippur, when our sins are forgiven.  What is this dependency between forgiveness and rain? 

As mentioned in the past from the Gra rain is not something that is built into the nature but comes from G-d Himself.  It is an other worldly experience.  The Gra explains in Berashis (2:6) that is why man must pray in order for rain to come down for it is not a natural occurrence but is dependent on the actions of man.  Now we can understand that rain will only come if one is deserving which is when one's sins are forgiven (based upon Yerach L'moadim siman 14.)  Now we can understand why the Mishna in Sukkah says that if rain comes on Sukkot it is like the master rejecting the service of his servant.  Why is that said only regarding rain on Sukkot and not any time one is stopped from doing a mitzvah?  Because if it rains it means that it is not nature stopping one from doing the mitzvah but it is Hashem directly coming to stop people from doing the mitzvah of sukkah that demonstrates His lack of desire for the mitzvah.