Indian summer offers last chance for a bit of heat

Our major weather change arrived in the Inland Northwest, but it was about a week earlier than expected. Although this recent pattern has been wet and cool, I do expect to see a number of days with warmer-than-normal temperatures and dry conditions between now and early November. This type of weather is often referred to as Indian summer.

Indian summer is an unseasonably brief, warm period that tends to occur in the midst of autumn in October or even into early November. It normally occurs just after the first hard freeze or immediately following an exceptionally prolonged chilly and wet spell.

In this part of the country, we usually see at least a couple of periods of warm, dry and hazy weather conditions during a typical fall season. Often, there are a few afternoons with record or near-record highs for the date, thanks mainly to a strong high pressure ridge over the region. This unusually mild air sometimes even reaches the normally cool and damp areas along the Washington and Oregon coastlines, providing some spectacular conditions for residents and tourists.

In Canada and the Northeast, a ground frost must be present before the onset of warmer weather for Indian summer to be declared.

There are a number of theories as to the origin of Indian summer including:

• The term originated from raids on European colonies by Indian war parties that usually ended in autumn.

• Ships traveling in the Indian Ocean loaded their cargo during the fair weather season, or Indian summer.

• It might be the traditional period which early Native Americans harvested their crops.

In Europe, the warm and dry periods of autumn are called “old wives” summers. These late-gleaning seasons near the shores of the Mediterranean Sea have gone on now for more than 5,000 years in places, including Israel, Italy, Spain and Greece.