Is it permissible to say, “You got a cold because of changes in the weather”?
Question

What is the ruling on one person saying to another who caught a cold: “You got a cold because of changes in the weather”?
Praise be to Allah.In the answer to question no. 105349, we noted that causes lead to effects –  so when the cause is there the effect will happen, otherwise it will not – because Allah, may He be exalted, has ordained that the cause should lead to the effect. Moreover, both cause and effect are created by the decree of Allah, may He be exalted, then if He wills, He lets the course lead to the effect, and the effect occurs, or, if He wills, He prevents that. So whatever Allah wills happens, and whatever He does not will does not happen, and neither the causes nor anything else of His creation has any impact on anything in His universe and creation independently of Him. Rather everything is under His control and is subject to His universal decree.
The changes in the weather that you mention are one of the causes which Allah has ordained may have an impact on people and make them catch colds and flu. The connection of effects to causes is in accordance with the wisdom of Allah, which is one of His attributes.
So the one who says that changes in the weather are one of the causes of catching a cold, believing that this happens by the decree of Allah, is correct and there is nothing wrong with what he says or believes in that regard.
What may be wrong in this regard is believing that the cause has an impact in and of itself, or attributing what happens to the weather and forgetting that Allah is the one Who decreed that and created it, in accordance with His wisdom in the universe.
A similar mistake is denying the connection between causes and effects, and that causes lead to their effects because Allah has ordained that these effects should be the result of the causes.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
With regard to what people believe about the matter of causes and effects, there are two extremes and a middle path.
The first extreme is denying that causes have any impact, and regarding them as no more than the signs at which the effects occur, and the effects do not occur because of them, to the extent that they said: If glass breaks when hit by a stone, that happens at the moment when the stone hits the glass, and not because of the stone hitting it.
These people’s view is contrary to the religious texts and it goes against what is seen and experienced. They deny the wisdom of Allah, may He be exalted, in connecting effects to their causes.
The second extreme is affirming that causes lead to effects, but they went to extremes in that and said that the causes in and of themselves lead to the effects [independently of Allah].
These people have committed shirk, because they believe that there is another creator with Allah. And they go against the religious texts and what is seen and experienced. The Qur’an, the Sunnah and the consensus of the ummah indicate that there is no creator except Allah, and we know on the basis of what we have experienced and seen in our own lives that causes may sometimes not lead to their effects, in accordance with Allah’s will, as the fire did not burn Ibraaheem al-Khaleel when he was thrown into it. Allah, may He be exalted, says (interpretation of the meaning):
{O fire, be coolness and safety upon Abraham} [al-Anbiya’ 21:69].
Hence it was cool and safe, and he was not burned by it.
As for the middle path, this is followed by those who are guided to the truth and they followed a middle path between the two extremes. They agree with whatever of truth each party has and affirm that causes may have an impact and lead to effects, but they cannot do that by themselves; rather it is by means of what Allah, may He be exalted, has instilled of them of forces that leads to that." (Majmoo‘ Fataawa wa Rasaa’il Ibn ‘Uthaymeen  4/207-208).
And Allah knows best.