The Beekeeper’s Companion Since 1861
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Honey Bee Biology

Weather Prediction Technologies Improving the Care of Honey Bees

- March 1, 2017 - Wyatt A. Mangum - (excerpt)

Maple Tree in Bloom

In late February, certainly by early March, the bees and I have become restless. We both feel it. Early Spring has finally arrived to the woods around the hives in Virginia, the eastern Piedmont region.

Contemplating the first hive inspections of the season, the nagging worry would be: how well did my bees survive the Winter? And for the colonies still surviving: were they weak or strong? Remarkably, I do not have this old uncertainty, lingering over the Winter any longer.

Recently, I have begun using thermal cameras with my bee management. Beginning in the Fall, and all through the Winter, I monitor my winter clusters. I can tell the cluster locations in my top-bar hives. I can even roughly tell the cluster sizes. I can tell when a cluster begins to dwindle, become smaller, shift position too quickly in the hive, indicating a problem.

Even at night in the cold, I am out in my rural apiaries checking on the winter clusters, never needing to disturb the bees. In a sense, I remain active with my bees, instead of leaving them when the weather turns cold. Last year, in the Winter of 2015/16, I knew my colony losses were 11%, long before I began my first Spring inspections. The thermal camera lets me know my colony losses early on, so I can plan for them. Early detection is the key.

I apply the same early detection methodology to another uncertainty in beekeeping–the weather. I try to anticipate what weather conditions are coming a week, or even up to a month, ahead. Too often early Spring begins with wide swings in foraging conditions. One day the weather is normal, temperatures typical, aided by warm winds from the South. My bees forage on maple trees scattered through the woods, still leafless (see Figure 1). The next day snow covers the maple blooms (see Figure 2). To better care for my bees, I want advanced warning for this kind of upheaval and other poor weather conditions that could damage my bees during the rest of the season.

I evaluate the weather at three broad levels using climate models, the jet stream, and local conditions. First, I watch two climate models that forecast the temperature and precipitation for the next month. The National Weather Service, Climate Prediction Center (One-Month Outlook), maintains the models, which predict for the 48 contiguous states and Alaska (a link from that web page goes to a text description for Hawaii). Figures 3 and 4 show the prediction maps for January 2017. The bottom left corner of the maps has the prediction month. The bottom right corner has the legend of the map. The model divides up the maps depending on the predictions. For either map, “A” indicates above normal; “B” indicates below normal; and “N” indicates normal. An “EC” indicates an equal chance of all other three possibilities (A, B, and N). For January 2017, the climate models predict Virginia will be warmer than normal, along with the East Coast and Gulf Coast States. The climate models report “Equal Chance” for Virginia’s precipitation for January 2017.

I watch these climate models all year. We have a short intense main nectar flow, beginning in late April, and ending around mid-June; the dates of course vary by season and even apiary location. Most of the best nectar flow is in May. While I do not want a full-out Spring drought, a predicted May drier than normal is all right with me. Too often colonies have a flood of nectar coming in (from black locust and tulip poplar) and a cold rain cuts it off. Colonies that were gaining 4-5 pounds per day go to losing a pound or two a day. If I were planning to bottom super with foundation and such an interruption were coming, I would delay supering in most cases, rather than break up the colonies. (In the cold, frames of foundation, which are not very attractive to the bees, form a barrier between the bees up in the supers and the bees below in the brood nest.)

On the other hand, I move my top-bar hives to large cotton farms in southern Virginia, a two-hour drive from my home apiaries. Cotton begins blooming in July. Since dry Summers loom like a constant threat, I watch the monthly climate forecasts leading up to July. I want to know the precipitation forecast even before cotton blooms, definitely for June. For example, if June was actually a wet month and predicted so, a predicted July above normal in precipitation is a very favorable indicator for a cotton nectar flow. If those predictions continued for August, and I could move more hives to cotton, I would do it since cotton blooms well into late Summer.

Because of the transportation costs, and the time commitment, I am trying to move my top-bar hives only when conditions are optimal for cotton nectar production. In two years of collecting data, some of my three-foot long top-bar hives have gained 80-90 pounds on cotton. I am building more five-foot long top-bar hives, managing them strictly for honey production aiming mainly for cotton honey production. These hives can weigh up to 250 total pounds (50 pounds per foot with my top-bar hive dimensions). My data indicates a top-bar hive operation producing honey by the ton is quite feasible, but it starts with the Climate models. (I have been publishing my top-bar hive honey production data on my website at; use the link “Top Bar Hive and Honey Production.”)

The position of the polar jet stream has a large influence on my bee management decisions, most importantly in the Spring. In the Northern Hemisphere, confining our attention to the United States and Canada, there are two jet streams, the polar jet stream to the North and a Subtropical jet stream to the South. The polar jet stream, which for simplicity I will just call jet stream, is the important one. The jet stream is a somewhat confined region of high wind speeds dividing colder temperatures to its North from warmer temperatures to its South. The jet stream winds blow eastward, and most critically, patterns in the stream move East too. A pattern might be a straight part of the jet stream moving due East, say well North of Virginia, maybe near to the Canadian border. In that situation, I would expect warm seasonable weather to prevail in Virginia. And in the late March with clear skies, my bees would be foraging on …