Little effect on classical/medieval tactics (they had similar items already)
<PERSON> & <PERSON> (Greek Fire & artillery)
First, I'm ignoring using fire in windy conditions.
As this is one of the main weaknesses of fire as a weapon. Due to the fact that wind could cause the smoke & even the fire itself (if not the spell then the stuff it lite on fire) to turn back at your own army. While rain would prevent you from lighting structures on fire defeating the main purpose. You simply would not use fire in windy or bad weather conditions.
<PERSON>
To start with firecone wizards: Greek Fire was a known substance during the classical period which allowed for the first real flamethrowers (though there were thermo-based weapons before this). It was a powerful weapon which could not be put out with water alone (it actually burned on the water).
Now at the 800-2000 degree (F, 1000 C) range - this would not really effect the tactics in use during the periods you proposed as Greek Fire tubes were about this temperature and with much greater ranges1. Again, these were limited due to the fact that they could not be used during bad weather and armies developed tactics to counter it including soaking hides or leather armor in vinegar to prevent ships from burning.
Now most stone melts at 2750 F, so anything over 2000F (1000C) could be a game changer. Destroying naval ships and melting castle walls. Except, the Middle Ages already had a similar game changer in the form of cannons. So it might lead to Bastion or Star forts being developed earlier and other anti-cannon tactics just coming sooner.
Firebolt
Now as to firebolt wizards, we called these grenadiers. 523
And these wizards were great at storing Greek fire in stone, ceramic, or glass jars to then lob firebolts into their enemies2. And again cannons, trebuchets, and catapults were already effective weapons which forced armies to develop tactics to protect their personnel & structures against them.
So again, at the same temperatures as mentioned earlier, the tactics developed against grenadiers & catapults (anti-personnel weapons) would be employed with these. While the tactics developed to protect against trebuchet & cannons (full artillery) would be employed against the other.
Possible high damage but not a lot of effect - Ice
Okay, you hit hypothermia way before your blood freezes and I assume that froze blood would be an unpleasant way to die - presuming that armor doesn't stop it. However, then you've only taken out 10 people per wizard.
The biggest advantage of this would be the fact that it is not effected by weather - meaning you could just snipe people on top of castle walls (in a full storm). Deadly but limited potential. Further, they would just start putting shields in front of themselves, arrow slits, or use other tactics which they had for dart launchers (i.e. catapults).
Destructive today - devastating during classical/medieval period
Tornado
Hurricane Dorian had sustained winds of 185 mph during its peak - this would be sending a high category hurricane against the enemy. Damage - look at hurricane aftermath or just imagine trying to ride on a horse, in full armor, through one.
Sources
1: <PERSON>, <PERSON> (2006), ""Greek fire" revisited: recent and current research", in <PERSON>, <PERSON> (ed.), Byzantine Style, Religion and Civilization: In Honour of Sir Steven Runciman, Cambridge University Press, pp. 290–325, ISBN 978-0-521-83445-2
2: <PERSON>: "Studies in Ancient Technology," Leiden 1993, ISBN 978-90-04-00621-8, p. 107 179