All About Howth / Environmental data

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Environmental data


To the north of the garden, the Hill of Howth provides important shelter from cold northerly winds. On the south side the land extends down to high watermark. This fortunate situation along with the influence of the warm North Atlantic drift is responsible for the favourable microclimate.

Air frosts occur regularly generally between early December and mid April. The lowest winter minimum is usually about -4º C but more severe frosts occur from time to time and we recorded low temperatures of -7.5º C in December 1995 and -7.0º C in December 2000. Freezing days, when the temperature does not rise above 0º C, are rare. Because of the proximity of the sea, summer temperatures are moderate, seldom exceeding 25º C. The absolute maximum recorded since 1969 was 28.9º C in July 2016, though this level of high temperature is very rare. Average annual rainfall is only 650 mm but this is spread fairly evenly throughout the year and periods of drought are rare.

A summary of the key meteorological data for the period 1969 - 2017:

Description Details
Lowest absolute minimum temperature - 6° C (Dec31/Jan1,1978/79)

- 6° C (Jan 13/14, 1987)

- 7.5° C (Dec 26/27. 1995)

Highest annual absolute maximum + 28.9° C (Jul 2016)
Annual average rainfall (spread over all months) 650 mm

Although rainfall is among the lowest in Ireland, the coastal location is responsible for relatively low daily maximum temperatures. Consequently drought is seldom a problem, the top soil remains relatively moist during the average growing season and trees and shrubs produce a preponderance of shallow, surface feeding roots.

Soil type

The soil is derived from Cambrian shale and quartzite. These are hard rocks and have enabled the peninsula to withstand the eroding action of the sea for millions of years. Had the peninsula been derived from limestone like most of the rest of County Dublin it would have been washed away long ago. The soil in the garden contains approximately 25% clay and 4.5% organic matter in the top 8 cm. It is mostly acid to neutral (pH 5.0 - 6.5) in contrast to the alkalinity of most of County Dublin.

Under these conditions and with the help of many organisations such as the National Botanic Gardens Dublin, Edinburgh Botanic Gardens , the UK Royal Horticultural Society and Abbey Gardens, Tresco, Isles of Scilly a large range of Climatic Zone 9 plants has been assembled. To obtain uncomplicated information on plant hardiness, no protection of any kind is given in the winter.

Howth Special Amenity Area Order - site of special interest

Howth Special Ameity Area Order - Sites of Special Interest

Fingal is an administrative area of County Dublin. The administrative area of Fingal is located to the north of the City of Dublin and extends in the west to the line of the River Liffey, to the east to the sea and to the north as far as the county boundary. It covers an area of approximately 173 square miles and has a population of almost 210,000 with growth projections to 260,000 by the year 2010.

In 1999 Fingal County Council recognised the exceptional character of the area of Howth by making the Howth Special Amenity Area Order [1]. The Howth Order was confirmed by the minister on the 16th May 2000.

Fingal County Council have listed the garden at Earlscliffe by name as a site of special interest that has to be maintained under the Howth Special Amenity Area Order. [2]

The following is taken from the Howth SAAO Factsheet‌: [3]

  • The Howth Special Amenity Area has a total area of 547 hectares.
  • It includes Ireland’s Eye (28 hectares) and the heathland, woods, cliffs, shingle beaches and wooded residential areas of the south-eastern half of the Howth peninsula (519 hectares). These areas have a rich diversity of flora and fauna, and include protected species such as the Green-winged Orchid and the Red Squirrel.
  • The Howth Special Amenity Area includes large and flourishing colonies of seabirds on Ireland’s Eye, and on the cliffs of Howth Head between Balscadden Bay and the Baily Lighthouse. These seabird colonies are among the largest in the country, and include species such as kittiwakes, guillemots, razorbills, cormorants and gannets.
  • The order designates a 21 kilometre network of rights-of-way as public footpaths. Every large area of heathland and woodland on the peninsula can be reached by these paths. These footpaths are shown on SAAO Map A.
  • The order designates 35 sites and areas of special natural, historical, architectural, archaeological and geological interest. These sites and areas of special interest are shown on SAAO Map B.
  • If a property is included in the area of the SAAO for Howth then the exemptions from planning permission under Class 1 of the Planning & Development Regulations 2001 do not apply. In practice this means that most types of development require planning permission from the planning authority. The Council’s Planning Department should be consulted before carrying out any works.

Ecology of Howth Head

The following is taken from the Howth Special Area of Conservation (SAC) Site Synopsis: [4]

A mosaic of heathland vegetation occurs on the slopes above the sea cliffs and in the area of the summit. This is dominated by Western Gorse (Ulex gallii), Heather (Calluna vulgaris), Bell Heather (Erica cinerea) and localised patches of Bracken (Pteridium aquilinum). In more open areas species such as English Stonecrop (Sedum anglicum), Wood Sage (Teucrium scorodonia) and Navelwort (Umbilicus rupestris) occur, along with some areas of bare rock.

The heath merges into dry grassland in places, with bent grasses (Agrostis spp.), Red Fescue (Festuca rubra), Cock's-foot (Dactylis glomerata), Yorkshire-fog (Holcus lanatus), Sweet Vernal-grass (Anthoxanthum odoratum), Lady's Bedstraw (Galium verum), Ribwort Plantain (Plantago lanceolata) and Yellow-wort (Blackstonia perfoliata). In the summit area there are a few wet flushes and small bogs, with typical bog species such as Bog Asphodel (Narthecium ossifragum) and sundews (Drosera spp.). Patches of scrub, mostly Hawthorn (Crataegus monogyna), Blackthorn (Prunus spinosa), Willow (Salix spp.) and Downy Birch (Betula pubescens), occur in places.

The maritime flora is of particular interest as a number of scarce and local plants have been recorded, including Golden-samphire (Inula crithmoides), Sea Wormwood (Artemisia maritima), Grass-leaved Orache (Atriplex littoralis), Frosted Orache (Atriplex laciniata), Sea Spleenwort (Asplenium marinum), Bloody Crane’s-bill (Geranium sanguineum), Spring Squill (Scilla verna), Sea Stork's-bill (Erodium maritimum) and three uncommon clover species: Knotted Clover (Trifolium striatum), Bird’s-foot Clover (T. ornithopodioides) and Western Clover (T. occidentalis).

Rock outcrops which are important for lichens are distributed widely around Howth Head. The richest area for lichens appears to be around Balscadden quarries. In addition, the Earlscliffe area is of national importance for lichens and is the type locality for the black, yellow and grey lichen zonation. [5]

A number of Red Data Book plant species, the latter five of which are legally protected under the Flora (Protection) Order, 1999, [6] have been recorded at this site - Green-winged Orchid (Orchis morio), Bird's-foot (Ornithopus perpusillus), Hairy Violet (Viola hirta), Rough Poppy (Papaver hybridum), Pennyroyal (Mentha pulegium), Heath Cudweed (Omalotheca sylvatica) and Betony (Stachys officinalis). [7]

Curved Hard-grass (Parapholis incurva), a species which had not previously been recognized as occurring in Ireland, was found at Red Rock in 1979.

The site is of national importance for breeding seabirds. A census in 1985-87 recorded the following numbers: Fulmar (105 pairs), Shags (25 pairs), Herring Gulls (70 pairs), Kittiwake (c. 1,700 pairs), Guillemot (585 birds), Razorbill (280 birds). In 1990, 21 pairs of Black Guillemot were counted. [8]

A number of rare invertebrates have been recorded from the site: the fly Phaonia exoleta (Order Diptera) occurs in the woods at the back of Deerpark and has not been seen anywhere else in Ireland, while the ground beetle Trechus rubens (Order Coleoptera) is found on storm beaches on the eastern cliffs. A hoverfly, known from only a few Irish locations, Sphaerophoria batava (Order Diptera), is present in the heathland habitat within the site.

The main land use within the area is recreation, mostly walking and horse-riding, and this has led to some erosion within the site. Fires also pose a danger to the site. There may also be a threat in some areas from further housing development.

Howth Head displays a fine range of natural habitats, including two Annex I habitats, [9] within surprisingly close proximity to Dublin city. The site is also of scientific importance for its seabird colonies, invertebrates and lichens. It also supports populations of at least two legally protected plant species and several other scarce plants. 

Disclaimer. Parts of the data found in these history pages are derived from sources currently available on the internet. In researching the previous owners of Earlscliffe, certain assumptions have been made as to the validity of this internet data. If you believe that some of this data is inaccurate, please contact .

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For more details of the garden at Earlscliffe, see the following pages

Howth Census data
Environmental data
Howth maps through the ages
Major Shipwrecks around Ireland 


This page was last updated on 27-Jul-2023