Your summon spells work better in the frostfell if you summon native creatures.
Prerequisites: Con 13, Snowcasting.
Benefit: In cold areas (temperature at or below 40° F), creatures native to cold environments and creatures with the cold subtype summoned by you are more powerful and agile than normal. The summoned creatures gain a +4 enhancement bonus to Strength and Dexterity for the duration of the spell that summoned them.
In areas of extreme cold (below –20° F), any summoned creature affected by this feat has maximum hit points when summoned.
Source: Frostburn, page 48.