yeast proofing

and whether you use °F or °C.    I would think that second temp group is almost killed off so it would be much slower if at all.

http://www.thefreshloaf.com/faqs/baking/yeast

fleischmans Usually recommends 110-20 for active dry and 120-130 for instant yeast.

here is a snippet that may answer your question that I found when looking to convert 28C to F

From The Inquisitive Cook, by Anne Gardiner and Sue Wilson with the Exploratorium (Henry Holt and Co., 1998).

300° F–400° F (150° C–205° C)
Surface temperature of a browning crust.

200° F (100° C)
Interior temperature of a loaf of just-baked bread.

130° F–140° F (55° C–60° C)
Yeast cells die (thermal death point).

120° F–130° F (49° C–55° C)
Water temperature for activating yeast designed to be mixed with the dry ingredients in a recipe.

105° F–115° F (41° C–46° C)
Temperature of water for dry yeast reconstituted with water and sugar.

100° F (38° C)
or lower When yeast is mixed with water at too low a temperature, an amino acid called glutathione leaks from the cell walls, making doughs sticky and hard to handle.

95° F (35° C)
Temperature for liquids used to dissolve compressed yeasts.

80° F–90° F (27° C–32° C)
Optimum temperature range for yeast to grow and reproduce at dough fermentation stage.

70° F–80° F (21° C–27°C)
Recommended water temperature for bread machines.

40° F (4° C)
Recommended refrigerator temperature. Used directly from the fridge, yeast is too cold to work properly.

Kind regards Derek

I hope you can repost this snippet in the yeast FAQs  (top of the page)  Get it up there at the top of the thread.  :)

Most interesting and a good refresher.  Thanks.