Polar Vortex temps are coming down to a neighborhood near us soon, with 3 days of temps below 20F with a low down to 1F, a relative first for us in Texas, so what's a mindful beekeeper to do?
Generally, in Central Texas, if your hives have enough food and you have not fed pollen supplements or weekly sugar syrup (which tends to induce early brood rearing), they should be fine...
Top-Bar hives made of 2" lumber are twice as insulated as hives made out of 1" wood and should be fine as long as they had food left last time you visited. Also, the horizontal configuration makes it much easier for the bees to have continuous access to their stores and is much more efficient at preserving the brood's nest conditions stable.
Top-Bar hives made out of 1" wood, especially with windows and thin bars are much less insulated and you might consider additional insulation (for example coffee bags draped over, old pillows filled with straw on top of the bars, etc.)
Langstroth hives with enough food and not too much brood should be ok as well. If worried, a piece of insulation board on top of the outer cover and a windbreak might help reduce the chimney effect. Make sure entrance reducers are in place, and no screened bottom boards (we recommend against those at all times anyway)
Other than that, the dice have been cast already: there is not much more that can be done at this point than stay out of your hives to preserve the propolis seals and wait and see - then check after warmer temps return (above 50F) and provide emergency feed (honey if possible, sugar bricks or heavy syrup if not, no pollen products) as needed, as they might have burned through a lot if they had a lot of brood started.
This being said, if brood rearing was not artificially induced by supplemental feeding and your bees are locally adapted, there should not be much brood present, and colony energy needs will be much, much smaller. Bees will be able to cluster tighter and not consume huge amounts.
Ironically, that's the beekeepers who have fed pollen (especially pollen patties and sugar bricks with pollen) or keep bees whose brood rearing cycles are not adapted to their local ebbs and flows of forage and weather that are most at risk of losing colonies to starvation. Colonies that have been artificially stimulated especially will have unseasonable amounts of brood, and in these frigid temperatures they will go through food stores very, very quickly to keep the brood's nest warm and the brood viable. That's a recipe for disaster that often leads to premature swarming at best, and starvation at worst. This is why we recommend emergency feeding only, and no pollen or weekly sugar syrup supplemental feeding too early in the season.
In summary, remember that:
Pollen supplements are best left to experienced beekeepers with specific goals and the skills required to mitigate the unintended consequences, especially since there is usually always pollen available in Central Texas throughout most of the year....
It's not the cold that kills bees in cold temps: it's humidity and brood rearing (leading to starvation).
we can't control environmental conditions and this too shall pass, so breathe and try not to worry too much!
Mother Nature knows best: trust the bees to follow the natural cycles of weather and forage!
Video and cover picture by USA TODAY - see the whole story here