Outreach - Irish Seasons

Irish Seasons

Seasonal configuration of the Earth and Sun

This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.


Winter: December/January/February

Has the coldest temperatures on average. More in darkness then in light, preventing good warming of the soil, grass will die back any growth through the period is generally minimal and of poor quality.

There can be settled or unsettled periods, chance of frost, fog, ice, snow and storms. As the warmer air shift south, as well as the gradient of temperatures, and thus the jet stream sits over us or close by, it can at times produce blocking patterns, bringing frequent low pressures or on the flip side occasional long settled periods, if the temperature gradient and thus the jet stream weakens.

Climate change: Irelands winters are likely to become milder, wetter, and also possibly stormier. While it may also bring periods of more extreme swings, such as much colder or much warmer weather, however generally the extremes will be short lived. Milder conditions will lead to fewer frost nights.

Farming: With low radiation from the sun and less sunshine hours, growth is halted or become very slow. Most crops and plants become dormant or have substantially reduced growth. Having an adequate supply of feed is important and that must be considered during the spring and summer leading up to it. With climate change the growing season will likely extend, meaning animals may be able to stay out longer, as long as the ground conditions are not too wet. Warmer conditions will likely cause more confusion to plants flowering or trees budding that could cause stress for them. It will also bring higher stress to animal increasing the risk of disease and illness as animals are in sheds. While cold snaps may lead to illness as well as a higher demand on meal, silage and hay. While conditions are expected to become generally milder, this also usually means wetter too so an extended growing season is of no benefit and if it is too wet animals may need to be housed sooner. Maintenance is a big part of the winter schedule, such as cutting hedges, drain maintenance and fencing, among other things, but only when soil conditions allow it. 


Spring: March/April/May

Transitional period between winter and summer, this can bring very unsettled periods as the battle for the colder polar air and the warming tropics increase the jet stream strength. The most unsettled conditions traditionally would come at the start of the season, but they are by no means limited to this period.

The old saying about March: In like a Lion and out like a lamb may not always play to the script but generally as the days lengthen and the grown and air modify temperatures conditions become less unsettled.

Climate Change: Stormy and wet periods could increase in the spring time, but also there is the chance that a dry end of spring and start of summer could cause drought to set in.

Farming: Spring is a busy period on farms as animals go out, crops are sown, fields are fertilized and prepared for silage and the spraying season begins.

Wetter conditions can make for poor trafficability on land and this can delay all of the above and may hinder already sown plants. While drought conditions can slow growth or in some cased cause crops to fail. Also for gardening and tree growth. Late frosts can also kill new growth and stunt tree growth. Ideally farmers prefer a slow transition to allow them to till or level the land, where the soil is firm enough to drive on, but moist enough to easily till, level or compact.  This year for instant brought a quick transition from saturation or waterlogged conditions to Agricultural drought.

Further climate information on Meteorological Spring is available in our 2023 article

Summer: June/July/August

As warm air from the tropics and longer sunshine hours increases mean temperatures, the colder air is shifted north and the jet stream generally weakens. Usually the warmest temperatures are recorded in the summer months. A weaker jet stream can lead to a more amplified jet and blocking patterns, where similar conditions persist for a longer period of time, can develop. This can bring long settled periods, with warm or hot conditions and prolonged drying leading to or exasperating drought. On the flip side if the high pressure is displaced away from Ireland, this allowed frequent low-pressure systems to bring unsettled conditions to Ireland.  While these lows generally do not pack the same wind threat, they can often carry the potential for extreme rainfall totals and thunderstorms. This summer we say a switch from a blocking high in June bringing warm, dry, settled conditions, before it moved southeast over the Mediterranean while blocking again and leading to wet and unsettled conditions that persisted from the end of June through much of August.

Climate change: Most likely climate change will lead to drier warmer summers on average, increasing the risk of drought. However year on year, or even within the one summer period that could switch from one extreme and the other like heavy rainfall, increased instability and thunderstorm activity, both of while could increase the chances of flooding or flash flooding. This can be exasperated but heavy rainfall falling on very dry soil which can lead to quick run off and flashier flooding. Tropical systems may become stronger while there is uncertainty about and increase or decrease in the number of storms. Especially in the latter part of the summer, Tropical activity, without even coming close to Ireland can lead to quick pattern shifts like the breakdown a blocking pattern. An increase in sea surface temperature in will likely increase the chances of tropical systems developing and maintaining strength further to the north and west of there traditional breeding grounds. While storms may maintain their tropical characteristics further north and potential bring an increased risk of violent winds (during extratropical transitions) but more so extreme tropical rainfall that could bring widespread flooding.

Farming: Neither drought nor flooding are conducive to developing crops, animal welfare or harvesting. Warm moist conditions with frequent rainfall can lead to potato blight and other diseases.  Heavy rainfall can pose a threat to crops, cereal crops can lodge. While summertime hail is quite rare in Ireland, climate change could increase in the chance of hail, or even large hail, posing a threat to animals, property, and crops, some flattened, while others could be stripped of their produce.

Autumn: September 1st to November 31st

As daylight hours in the northern hemisphere decrease, cooler conditions spread from the north pole and as the gradient between cold air to the north and the warmest period in the tropics another transitional period begins between summer and winter. This can bring very unsettled periods at any point in the season traditionally though they would be greatest towards the end of the period. The difference in Autumn is that tropical systems developing in the Atlantic traditionally between 8deg north and 20 north of the equator. They can have a major impact on our weather patterns, without even coming close. They can at times lead to an Indian summer (like this year). However there is also the threat of the remnants of these tropical systems bringing stormy conditions to Ireland, either making a extratropical transition to a strong storm, combining with an extratropical low to the same end, or, From the latent heat, which is basically energy being transported from the tropics into the upper atmosphere and to the north. This can lead to a stronger more unstable jet stream, and in turn spawn rapidly developing extratropical lows).

Climate Change: Much like with spring the extremes will increase, the potential for stronger storms and more unsettled conditions. Extreme rainfall and increased thunderstorm chances may continue later into the Autumn as a warmer atmosphere can carry more and larger raindrops.

While settled dry conditions can either develop or prolong drought.

Farming: Generally, the harvest is in its busiest period at the start of the season and gradually tapers off through October with some root crops carrying through to early November. The length of the growing season is important for finishing animal and combined with ground conditions can determine the length of time animals can remain out on the land before wintering. Grass quality though will diminish as the season progresses and as sunshine hours reduce. Ground conditions will also play into the cultivating and sowing of winter crops (to be harvested earlier next summer, usually July).