What is Bronte's use of fire and ice in chapter 26?

Fire and ice are strong motifs in Jane Eyre. Both symbolise Jane in different ways. Fire symbolized Jane's temperament and passion while ice symbolizes the forces that try to defeat her fiery spirit. Jane compares her mind to a "lighted heath". This, of course, makes her susceptible to the cold forces in her life. Just after Jane finds out that Rochester is already married to some girl named Bertha, the cold forces envelop her,

“A Christmas frost had come at mid-summer: a white December storm had whirled over June; ice glazed the ripe apples, drifts crushed the blowing roses; on hay-field and corn-field lay a frozen shroud . . . and the woods, which twelve hours since waved leafy and fragrant as groves between the tropics, now spread, waste, wild, and white as pine-forests in wintry Norway. My hopes were all dead." (Chapter 26)

Sure that sounds a bit on the melodramatic side but it is who Jane is. Jane was prone to these intensities of emotion. Fire and ice are strange bedfellows and they are forever at odds inside Jane.