what season is easter in? is it spring?

how about thanksgiving day? what season is that in?

How's the weather in winter for Alaska and Seattle?

Easter is always in spring. Thanksgiving is also in fall.

Winter weather in Alaska depends a lot upon where you live, since the state is so large and has a wide latitude range. It is cold, of course, but along the southeast panhandle, (such as Juneau and Ketchikan) the temperatures are relatively mild.
Seattle has very mild winters, but gets some rain or light showers on most winter days. Daytime high temperatures are usually above freezing in winter, and snow rarely gets more than a few inches deep or stays on the ground more than a week. There are high mountains nearby with year-round skiing.

The "official" periods of the seasons are the astronomical definitions, not the ones defined by insolation (solar heating) from the referenced cited by SrJMcGin. These are the dates you will find printed on calendars, for example. The astronomical definition, from the same article, is:

<Astronomical
In astronomical reckoning, the seasons begin at the solstices and equinoxes...

In the conventional United States calendar: Winter (89 days) begins on 21 December, the winter solstice; Spring (92 days) on 20 March, the vernal equinox; Summer (93 days) on 20 June, the summer solstice; and Autumn (90 days) on 22 September, the autumnal equinox. (These dates can vary by one day due to leap year effects)

Easter is typically celebrated during the spring season. It is a movable feast that falls on varying dates each year, determined by the lunar calendar.

Thanksgiving Day is always celebrated on the fourth Thursday of November. Therefore, it is during the autumn season, specifically in late fall.

As for the weather in winter, Alaska and Seattle have quite different climates due to their geographical locations.

In Alaska, particularly in the northern parts, winter weather is extremely cold with temperatures commonly dropping below freezing. It experiences long periods of darkness and heavy snowfall. In contrast, coastal areas of Alaska, such as Anchorage, have milder temperatures due to the marine influence.

Seattle, on the other hand, has a more moderate climate compared to Alaska. Winters in Seattle are typically cool and wet, with temperatures ranging from above freezing to the mid-40s Fahrenheit (4-7 degrees Celsius). Though it experiences periodic rain showers, snowfall is rare and tends to be minimal, if any.

It is important to note that weather conditions can vary from year to year, so it's always a good idea to check a local weather forecast for the most accurate and up-to-date information.