阻塞高气压是暖性高气压，长时间滞留在同一地方而且稳定；这些阻塞高气压持续时间多于5天，令受它们影响的区域有一段长时间相同的天气（如部分地区出现持续降水) 。 在北半球，阻塞高气压最常于东太平洋和大西洋的春天时出现。阻塞高压创建前，西风波动振幅会增加而波长缩短。完整环流及闭合等压线之高压由西风脊隆起加强发展而成，因振幅剧烈，通常与副极地低压一同出现。

阻塞高气压出现时，会令西风带出现异常型态，主要影响为西风气流分开南北两个支流，引致副极地低压南下，阻塞高气压附近引导气流弱，会阻碍地面天气系统移动，会间接引致起寒潮、暴雨等极端气候出现。

Blocks in meteorology are large-scale patterns in the atmospheric pressure field that are nearly stationary, effectively “blocking” or redirecting migratory cyclones. They are also known as blocking highs or blocking anticyclones. These blocks can remain in place for several days or even weeks, causing the areas affected by them to have the same kind of weather for an extended period of time (e.g. precipitation for some areas, clear skies for others). In the Northern Hemisphere, extended blocking occurs most frequently in the spring over the eastern Pacific and Atlantic Oceans.