Defining the seasons
There are two basic definitions of the seasons and they are six weeks out of line with each other.
From a solar perspective (and also a farming, countryside, and neo-Pagan one) the seasons change on the cross-quarter days, thus:
Winter: 31st October to 2nd February (Samhain to Imbolc), with Midwinter's Night (the longest night / shortest day) bang in the middle on 21st December.
Spring: 2nd February to 1st of May (Imbolc to Beltaine), with the Spring Equinox bang in the middle. This roughly coresponds with most plants coming to life again after the Winter.
Summer: May 1st to 2nd August (Beltaine to Lammas), with Midsummer's Day (longest day / shortest night) bang in the middle on 21st June.
Autumn: 2nd August - 31st October (Lammas to Samhain) wth the Autumn Equinox bang in the middle.
However, the "official" seasons seem to be:
Winter: Midwinter's Night to Spring Equinox.
Spring: Sprint Equinox to Midsummer's Day.
Summer: Midsummer's Day to Autumn Equinox.
Autumn: Autumn Equinox to Midwinter's Day.
Personally I think the solar / pagan version makes a lot more sense and not just because I'm a pagan, but because it better reflects both the solar situation and the growth of crops and plants. I think the reason for the "official" dates is because the amount of heat we feel lags behind the sunlight to a degree (and usually by about six weeks) - so for example even though we have long days from 1st of May onwards it usually takes till mid-June before the weather starts to feel really warm, and even though the days start to get shorter from Midsummer onwards, it's at least August and often September before we actually start to notice the weather turning colder - before that there's still enough heat arriving from the sun to keep temperatures rising even though the days are shortening. Same thing happens in February - the days are lengthening but it's mid-March or later before we start to notice the temperatures rising.
From a solar perspective (and also a farming, countryside, and neo-Pagan one) the seasons change on the cross-quarter days, thus:
Winter: 31st October to 2nd February (Samhain to Imbolc), with Midwinter's Night (the longest night / shortest day) bang in the middle on 21st December.
Spring: 2nd February to 1st of May (Imbolc to Beltaine), with the Spring Equinox bang in the middle. This roughly coresponds with most plants coming to life again after the Winter.
Summer: May 1st to 2nd August (Beltaine to Lammas), with Midsummer's Day (longest day / shortest night) bang in the middle on 21st June.
Autumn: 2nd August - 31st October (Lammas to Samhain) wth the Autumn Equinox bang in the middle.
However, the "official" seasons seem to be:
Winter: Midwinter's Night to Spring Equinox.
Spring: Sprint Equinox to Midsummer's Day.
Summer: Midsummer's Day to Autumn Equinox.
Autumn: Autumn Equinox to Midwinter's Day.
Personally I think the solar / pagan version makes a lot more sense and not just because I'm a pagan, but because it better reflects both the solar situation and the growth of crops and plants. I think the reason for the "official" dates is because the amount of heat we feel lags behind the sunlight to a degree (and usually by about six weeks) - so for example even though we have long days from 1st of May onwards it usually takes till mid-June before the weather starts to feel really warm, and even though the days start to get shorter from Midsummer onwards, it's at least August and often September before we actually start to notice the weather turning colder - before that there's still enough heat arriving from the sun to keep temperatures rising even though the days are shortening. Same thing happens in February - the days are lengthening but it's mid-March or later before we start to notice the temperatures rising.