MAINE weather, above all, is changeable. A classic Maine line is “If you don’t like the weather, wait a minute.” This is because Maine’s weather is influenced by a number of factors, each affecting the others. General weather patterns, effects of ocean temperatures and offshore winds, and local conditions such as a bay, a landmass, or a warm river current can dramatically change the weather in the immediate vicinity. COPYRIGHT 2006 DIAMOND PASS PUBLISHING Wind.On a typical fair-weather summer day, morning winds are light. As the sun rises and warms the air over coastal landmasses, the wind gradually fills from the southwest, and by mid-afternoon it can reach 15 or 20 knots, though often less, before weakening by sunset. The force of these afternoon sea breezes should not be underestimated. Lobstermen begin hauling their traps at dawn to avoid the chop of the afternoon. Skippers of small boats should do the same, planning their most exposed roundings or passages before noon and stopping early. COPYRIGHT 2006 DIAMOND PASS PUBLISHING If the sea breezes should veer slightly to the southeast or east, they will pass over the cold currents from the north, which will condense the moisture they carry into thick fog. This transformation can happen in a matter of minutes, not hours, so have a “fog plan” in the back of your mind at all times to help you decide where to run when you can’t see anything (see “Fog” below). IF YOU ARE READING THIS, YOU HAVE VIOLATED Northwest winds carry little or no moisture and are generally clearing winds associated with cold fronts. They bring sparkling weather, but often gusty conditions. The strongest gusts blow just after the cold front has passed, after which they tend to taper off and shift to the southwest. INTERNATIONAL COPYRIGHT LAW. The shape of coastal landmasses can affect wind in many different ways. They can physically redirect or block the wind, create a sheltered lee, or funnel the wind and accelerate it through constrictions, a phenomenon known as the Venturi effect. Landmasses can also produce aerodynamic effects like downdrafts, where wind passing over a land is deflected down the lee side of the landmass, or wind wrap, where wind may change direction at a point by wrapping around it. PLEASE RESPECT AND SUPPORT THE WORK THAT HAS Landmasses can also affect the wind thermally. When a warming landmass heats the air over it, the rising hot air can interrupt the windflow over the land, or the rising air can create a wind of its own as cooler wind rushes in to fill the vacuum it has left. BROUGHT YOU THIS INFORMATION. BUY THE GUIDE! The result of all these landmass effects is that wind will always have a strong local influence. One bay or cove may be windy while another is calm, or the wind direction or strength in one place may be quite different than its direction or strength in another place nearby. Boaters must remember that calm winds at the launching site do not mean that it will be calm off nearby points or offshore. COPYRIGHT 2006 DIAMOND PASS PUBLISHING Above all, boaters should consider the wind’s effect on the water. The greater the distance the wind travels over the water, called “fetch,” the larger the waves it creates. Likewise, the shallower the water, the steeper the chop. And if the wind is opposing any current, the waves will be even steeper (see “Tides and tidal currents,” below). COPYRIGHT 2006 DIAMOND PASS PUBLISHING Fog.Fog is a fact of boating life in Maine. Southeasterly or easterly winds are typically moisture-laden, having picked up their wet cargo as they crossed the warm Gulf Stream. Once they encounter the cold waters in the Gulf of Maine, their moisture condenses into thick fog. Fog generally is most prevalent during mid-July, then it tapers off toward September as the Maine waters warm. IF YOU ARE READING THIS, YOU HAVE VIOLATED Fog does not need to be intimidating, but it warrants careful coastal navigation and planning by boaters. Often, small boats can escape the fog on warmer bodies of water such as shallow or protected bays and coves or rivers. More on fog. INTERNATIONAL COPYRIGHT LAW. Gales.The strongest winds during the spring and summer are produced by fronts and thunderstorms, often from the south and southwest. These can reach 20 or 30 knots or more, and they can build quite suddenly. If you see disturbances in the skies to the south and southwest, make plans to avoid being on the water, or be ready for a prompt landing in a protected area. PLEASE RESPECT AND SUPPORT THE WORK THAT HAS Hurricanes. Hurricane season along the entire Atlantic coast runs from June through October. Historically most hurricanes that have hit Maine arrived in late August or September, and they have often lost some of their strength by the time they arrive. Hurricanes are tracked from their inception in the Gulf of Mexico and the Caribbean, so generally they will be forecasted several days ahead of their arrival. More information about hurricanes in Maine. National Hurricane Center BROUGHT YOU THIS INFORMATION. BUY THE GUIDE! Forecasts.Weather-watching is a universal preoccupation with Mainers, and Maine’s forecasting infrastructure is excellent on both local and network TV, radio, and the web. National Ocean and Atmospheric Administration broadcasts updated forecasts 24 hours a day on VHF channels 01, 02, and 03 and by phone at 207-688-3210. These forecasts paint excellent pictures of large-scale weather patterns, but they often will not accurately reflect local conditions, which may be more benign or more dangerous. Kayakers should use the forecasts as guidelines only, weighing them against your local observations of weather conditions and your prudent judgement.