Porthmadog Temperature by Month

The average annual maximum temperature in Porthmadog, Gwynedd, United Kingdom is 13°C (55°F), with daytime highs ranging from 8°C (46°F) in January to 19°C (66°F) in July. This page covers monthly averages, day-night differences, and how Porthmadog compares to cities worldwide.

In Porthmadog, seasonal changes bring about a moderate variation in temperatures. Nighttime lows range from 12°C (54°F) in July to 3°C (37°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in Porthmadog by month:

The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. July, the warmest month, gets 155 hours of sunshine.

The chart below shows the average temperature throughout the year:

Porthmadog's average annual maximum temperature is 13°C (55°F). To put that in context, here's how it compares to a few well-known destinations:

Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.

On the cooler end, Oslo, Norway averages just 10°C (50°F) annually, with pleasant summers but long, cold winters.

San Francisco, USA averages 19°C (66°F) annually, but with little seasonal variation, summers are often cool and foggy, winters mild.

Melbourne, Australia averages 20°C (68°F) annually, known for unpredictable weather, with four seasons sometimes happening in one day.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Whether a city sits on the coast or deep inland makes a significant difference to its climate. Coastal areas tend to have more stable temperatures year-round, large bodies of water absorb heat slowly in summer and release it gradually in winter, keeping extremes in check. Cities far from the sea don't benefit from that buffer, which is why continental climates tend to have hotter summers and colder winters than their coastal counterparts at the same latitude.

For more on Porthmadog's weather, including monthly rainfall, sunshine hours, and humidity, visit our Porthmadog climate page.