Assalamualaikum ustaz. During the rainy or monsoon season, most complain and grumble and some even cursed the rain itself because it disturbs and delays their work. Hope for an explanation.
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
We begin with the statement of Allah SWT:
وَنَزَّلْنَا مِنَ السَّمَاءِ مَاءً مُّبَارَكًا
“And We have sent down blessed rain from the sky,” 
Al-Baghawi stated the above verse means Allah SWT sent down water from the skies blessed with goodness and that it contains the life of everything and it is the rain. 
The weather in Malaysia is characterized by two types of monsoons, namely the Southwest Monsoon which begins from the end of May to September, and the Northeast Monsoon from November to March. The Northeast Monsoon brings heavy rainfall mainly to the states on the east coast of Peninsular Malaysia and west Sarawak, while the Southwest Monsoon shows relatively drier weather. The transition period between these two monsoons is known as the monsoon transition season.
The Northeast Monsoon season is the main rainy season in our country. The monsoon weather system that formed together with the cold air gusts from Siberia produced heavy rains that often cause major floods in the east coast states of Kelantan, Terengganu, Pahang and East Johor, as well as the state of Sarawak in East Malaysia. The Southwest Monsoon is relatively drier for the whole country except the state of Sabah in East Malaysia. During this season, most states experience minimal monthly rainfall, usually between 100 – 150mm. This situation indicates stable atmospheric conditions in the equatorial region. The dry conditions in Peninsular Malaysia are mainly due to the rain protection effect of the mountain ranges in Sumatra. Sabah is relatively wetter (over 200mm) as a result of the tail effects of typhoons that frequently cross the Philippines during their journey across the South China Sea and its surroundings. 
Cursing the Rain
Regrading this matter, there is a hadith from narration of Abu Hurairah RA where the Prophet PBUH said:
قَالَ اللهُ تَعَالَى: يُؤْذِينِي ابْنُ آدَمَ يَسُبُّ الدَّهْرَ:، وَأَنَا الدَّهْرُ، بِيَدِي الأَمْرُ، أُقَلِّبُ اللَّيْلَ وَالنَّهَارَ.
“The son of Adam injures me by abusing time, whereas I am time. Authority is in my hand. I vary night and day.” 
According to Imam al-Nawawi, scholars are of the opinion the phrase “(Allah) I am time” is a figurative speech (majaz). The reason is the Arabs will usually curse the time whenever calamity, disaster, incidents that results in death, ageing, destruction of property and other strikes. Hence, the Prophet PBUH said, “Don’t injure (curse) time for He is time” meaning don’t curse the Creator of incidents, for is you curse the Creator, then in actuality, the curse is returned to Allah SWT for He is the Creator and the One who sent it down from the skies. As for al-Dahr, is the time of which no actions are in it, furthermore, it is included amongst the creations of Allah SWT. Thus, the phrase “Allah is time” means the one who sent disasters, the creator of incidents and the creator of every creation. 
Ibn Kathir cited from al-Syafi’I and Abu ‘Ubaidah regarding their interpretation on the hadith that during the time of jahiliyyah, whenever the Arabs were struck by a calamity, they consider that everything that happened is due to time, then, they curse time, when in reality, everything is from Allah SWT. With their words, it is as though they curse Allah SWT because Allah SWT is the One who actually created everything. Thus, the act of cursing time refers to the meaning of cursing to equating every bad incident to Allah SWT who created it. 
Hence, this hadith is clear evidence that cursing time is the same as cursing the creator of time and the incident is from Allah SWT. Likewise, the act of cursing rain in truth is cursing Allah SWT who sent rain down during certain seasons or times. Thus, this act is clearly prohibited.
Actually, if harm occurs due to continuous rain, we are encouraged to supplicate with the supplication taught by the Prophet PBUH with the purpose of easing the heavy continuous rainfall. This is based on a hadith narrated from Anas bin Malik RA, he said:
بَيْنَا النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ يَخْطُبُ يَوْمَ الجُمُعَةِ، فَقَامَ رَجُلٌ فَقَالَ: يَا رَسُولَ اللهِ، ادْعُ اللَّهَ أَنْ يَسْقِيَنَا، فَتَغَيَّمَتِ السَّمَاءُ وَمُطِرْنَا، حَتَّى مَا كَادَ الرَّجُلُ يَصِلُ إِلَى مَنْزِلِهِ، فَلَمْ تَزَلْ تُمْطَرُ إِلَى الجُمُعَةِ المُقْبِلَةِ، فَقَامَ ذَلِكَ الرَّجُلُ أَوْ غَيْرُهُ، فَقَالَ: ادْعُ اللَّهَ أَنْ يَصْرِفَهُ عَنَّا فَقَدْ غَرِقْنَا. فَقَالَ: «اللهُمَّ حَوَالَيْنَا وَلاَ عَلَيْنَا» فَجَعَلَ السَّحَابُ يَتَقَطَّعُ حَوْلَ المَدِينَةِ، وَلاَ يُمْطِرُ أَهْلَ المَدِينَةِ
“While the Prophet (ﷺ) was delivering a sermon on a Friday, a man stood up and said, “O Allah’s Messenger (ﷺ)! Invoke Allah to bless us with rain.” (The Prophet (ﷺ) invoked Allah for rain.) So, the sky became overcast and it started raining till one could hardly reach one’s home. It kept on raining till the next Friday when the same man or another man got up and said (to the Prophet), “Invoke Allah to withhold the rain from us, for we have been drowned (with heavy rain).” The Prophet (ﷺ) said, “O Allah! Let it rain around us and not on us.” Then the clouds started dispersing around Medina and rain ceased to fall on the people of Medina.” 
According to the above discussion, in our opinion, cursing rain is prohibited. The reason is Allah is the One who sent down the rain and cursing rain in reality curses the essence that sends it down which is Allah SWT.
Furthermore, we should know that the original purpose of rain is a blessing from Allah SWT. Thus, every Muslim when he sees rain should increase his supplication so that it becomes beneficial rain as stated in a hadith narrated by Aisyah R.Anha, she said:
فَإِنْ مُطِرَ قَالَ: اللَّهُمَّ صَيِّبًا هَنِيئًا
“When the Messenger of Allah (ﷺ) saw rain, he would say: “Allahumma aj’alhu sayyiban hani’an (O Allah, make it a wholesome rain cloud).”