Following are a pair of spells that are intended to round out the weather manipulating skills of spell casters in OGL games. These are eminently suitable for use by the new Weather Mage prestige class. 

Change Temperature

Transmutation [Air]

Level: Drd 3, Sor/Wiz 3

Components: V, S

Casting Time: 1 standard action

Range: Centered on Caster

Area: 40ft. / Level radius cylender 40ft/level high

Duration: 1 hour/ level

Saving Throw: None (see text)

Spell Resistance: No

You change the temperature in the area around you. The temperature may either be increased or decreased, but must be evenly adjusted within the spell's area of effect.

Starting with the temperature level of the environment that the caster is in, the caster may move the temperature up or down one level per every three spell caster levels. The temperature levels are listed below (in degrees fahrenheit):

Extreme Cold (below -20 degrees)

Severe Cold (below 0 degrees)

Cold (below 40 degrees)

Moderate (between 40 and 90 degrees)

Very Hot (above 90 degrees)

Severe Heat (above 110 degrees)

Extreme Heat (above 140 degrees)

Anyone within the spell's radius of effect may need to make fortitude saves in order to resist the effects of exposure (as described in the DMG section on cold and heat dangers). After the spell is cast, the temperature changes within seconds and immediately begins to affect the environment as it normally would for the duration of the spell (water begins to freeze, snow becomes rain, etc).

This spell changes the ambient temperature of the air in an environment, and cannot be used to directly change the temperature of an item or substance.

Precipitation

Transmutation [Water]

Level: Drd 2, Sor/Wiz 2, Water 4

Components: V, S, See Text

Casting time: 10 Minutes

Range: Centered on Caster

Area: 1 Mile / Level

Duration: See Text

Saving Throw: None

Spell Resistance: No

You force all clouds within the spell's area of effect to release their precipitate. The resulting precipitation is dependent on the temperature and the environment that the caster is in, with a 70% chance that the resulting weather will be regular precipitation, 20% that it will be a storm, and 10% that it will be a powerful storm  (see DMG on weather).

This spell does not create clouds, if there are no clouds within the area of effect, then there can be no precipitation, and the spell fails. Precipitation only falls where there is cloud coverage. The duration of the precipitation is dependent on the type, with most precipitation lasting for 2d4 hours (see DMG on weather for the duration of other types of precipitation).