A summer colder than winter?

Question

Normally, summers are supposed to be hotter than winters because the axis of the Earth is tilted toward the Sun during the hot season. This mean that the north receive more energy from the Sun, days are longer and thus, it's hotter.

But I was wondering if some characteristics could make one area colder in summer (July in the north January in the south) than it is in winter compared to the rest of the same hemisphere.

• As a reference, I used July and January as the hottest months for the north and south hemisphere respectively.
• It can be anywhere on the planet.
• The area must be large enough, not just a mountain. It should be at least the size of a small country like Belgium.
• Ideally, I would prefer to avoid explanations that have their origin in space such as solar eclipses (anyway, I don't think it would work)
• The difference in temperature needs not to be large, 5 degrees will do.

Answer 1

It will depend on if you look at Max High, Average High, Mean, Average Low or Min Low temperatures.

Around Swakopmund, Namibia, that could be classified as being hotter in winter than in summer, especially if looking at Max High. Though in 2009 the Average High and Mean was hotter in winter than in summer (The mean only by 0.1 °C (0.18 F)). The nights was still colder in winter than in summer.

Average High Temperatures
In 2009 the Average High temperature for January was 19.9 °C (67.82 F) and for July was 24.5°C (76.1 F).

Mean Temperature
The Mean Temperature for the same Year was for January 18.2 °C (64.76 F) and for July 18.3 °C (67.94).

Maximum High's
The Max High temperatures for Swakopmund in July have for at least the past 8 years been far higher in July than in January, by as much as 10 °C (18 F). They even had an August Max of 47.3 °C (117.14 F), while January was only 23.8 °C (74.84 F).

In summer there is usually a sea breaze cooling the area, while some days in winter have a land breaze that blow all the desert heat into town.

Source:

Swakopmund Yearly Temperature Summary(°C)

Answer 2

Look for areas on Earth that have (nearly) uniform year-round temperatures, and see why it's the case. Then you can exaggerate the issues or combine them in your plausible fictional world.

One thing I can think of is Los Angeles, where air can come down from the mountains and heat up due to increased pressure. The city of Kunming is known as City of Eternal Spring because of its mild seasonal changes. Looking at the chart there is a 15° F difference between summer and winter. It is in an elevated basin, and Wikipedia mentions subtropical highland climate (Cwb) and you ought to read up on that and that suggests reading about weather "types" in general.

Find out what makes Cwb tick, and add:

• Surrounding weather patterns cause the air to drop 10000 feet from the mountains, just when it would have been coldest in winter
• Arctic fronts are funneled into the basin when it would have been warmest in summer.
• Lake gives inertia to keep the fluctuations dampened and averaged out.

In general, the weather patterns dominate over seasonal temperature.

Answer 3

An island within a strait that connects a large shallow high latitude sea to the wider ocean closer to the equator, maybe?

During summer the water of the sea warms and expands pushing a strong current of cold water to the strait. During winter the sea gets colder the water contracts and water from the warmer ocean is pulled into the strait. You can reinforce the effect by putting the island into a small sea in the strait and using mountains to weaken winds from north and south. This will make the effect of water temperature stronger. Maybe put the island within the sea near to where a warm current comes in during the winter?

Answer 4

If you are looking for a temperate climate, meaning non-tropical, that has an actual four season year the answer is no.

Now if the temperature swing you are looking for is minimal <10 degrees F, you could probably use the ideas/concepts in the other answers to get what you want.

But if you are looking for snow in the summer and scorching hot days in the winter you just can't naturally overcome the impact of the sun. It is, by orders of magnitude, the unquestioned dominant force on our weather. Without magic or hand-wavium you just can't beat it.

Answer 5

You could be looking for a weather phenomena similar to June Gloom, which is a weather pattern that happens yearly around June in southern California, resulting in overcast skies and cooler temperatures.

Something similar happen in the Pacific Northwest (Washington and Oregon) that is referred to as "June-uary".

Both happen because one area heats up in the summer, pulling cool air from over the ocean inland and mixing. This makes a lot of clouds, which blocks sunlight and causes a lot of cooling.
So, it gets colder because of the summer heat.