I went to the ARS azalea selector at:

http://www.rhododendron.org/search_multi_azalea.htm

and entered white, 2 foot, -10 F and it came up with:

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Carrie Amanda, Early Midseason bloom, 2 ft., -15 F, White, Pink

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Conversation Piece, Late Midseason bloom, 2 ft., -10 F, Purple, White

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Helen Curtis, LateMidseason bloom, 2 ft., -20 F, White

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Lady Robin, LateMidseason bloom, 2 ft., -10 F, White

Marie's Choice, Midseason bloom, 2 ft., -20 F, White

Here is a reference for Helen Curtis. It is probably your best choice.

Evergreen Azalea: 'Helen Curtis' (R. 'Desiree' x R. 'Rosebud')

Flower white without markings, widely funnel-shaped, semi-double with 10 frilled lobes, 2-1/2" across. Inflorescence 2-3 flowered. Blooms late midseason. Leaves broadly elliptic, acute apex, rounded base, 1-1/2" long, glossy, yellow-green, retained for 2 years. Upright, rounded habit. Reaches a height of 2 ft. in 10 yrs. Bud hardy to -20°F (-29°C). Hybridized by Shammarello.

Here is a link that might be useful: Helen Curtis

A cold hardiness study by the University of Tennessee was completed near the end of last year on the Encore Azaleas. Encore Autumn Angel sounds like it could be a good match for you. It has a solid white bloom, grows 3ft by 3ft and the study has shown that it consistently exhibited solid cold hardiness. I can't remember exactly, but I believe the study was conducted over a 3 year period. I found this information on www.encoreazalea.com

Thanks for the web site and the info. Interesting what some people call white. Lainey

The reason multi colors are included with white is because the word white is in their description. For example a white with red picote is included under both red and white. From a distance it would probably look pink, but that is not want it is classified as.