Could an arctic air blast (like what is currently punishing the upper midwestern US) theoretically plow through the US, into Mexico, down into Guatemala and Honduras and points south, plunging San José, Costa Rica into an unprecedented overnight low of, say, 45F?
Is there a theoretical bottom point of temperatures in tropical climates? What is the coldest temperature ever recorded in a sea-level city below 30 degrees latitude?
What JerseyFrank said. There’s (disputed) evidence that just under a billion years ago a bunch of new organisms in the oceans basically sucked all the greenhouse gases out of the atmosphere and kicked off an event that makes the last ice age look like a brisk morning. The entire planet was, so the hypothesis goes, covered in an ice sheet to a significant depth (the Wikipedia article doesn’t have a number I could see at a quick glance.
But that would have put temperatures in the tropics well below freezing and possibly below 0 Fahrenheit for quite some time.
Really cold air masses from the north never reach as far south as Panama, which is at 9 degrees north. Here in Panama City the lowest temperature recorded over the last 13 years was 68 F (20 C). I doubt it has ever gotten much below that in recorded history.
Of course it is cooler at higher altitudes. It may sometimes reach freezing at the top of the country’s highest peak, Volcan Baru, at a bit over 11,000 ft, and a few snow flurries have been seen there.
Of course there is permanent snow and ice in the highest peaks in the Andes.
Broome is at about 18 degrees south and regularly gets below 10C (50F) during winter nights. The coldest recorded temperature was 3.3C (38F) in 1966. The cold temperatures there have more to do with cold air off the desert than arctic flows.
Hurricanes are not likely to be the cause of cold temperatures as they are a warm weather pattern that form in moist tropical conditions over water when the sea temperature is approximately 26 degrees C or higher.
I’ll note that at the summit of Mauna Kea in Hawaii, snow is normal in winter, and occasionally there is enough for skiing. (It helps that the elevation there is 13,700’ - not the sea level specified in the OP.)
Echoing Colibri above … When I lived in Panama City in the 1980s the standard line was that the coldest temp ever recorded at the base met station since records began was 67F. And those records dated back into the 1920s.
Cape Canaveral is not considered tropical, it is not even near the 30 degrees from the equator mentioned in the OP. Freezes in mid and north Florida are not uncommon. The Tropic of Cancer (band between the equator and 30 degrees north latitude) is the northernmost area where the sun shines directly overhead in the summer. The only place in Florida that sits near the edge of the Tropic of Cancer is Key West and it’s never frozen there during recorded history.
Patterns of global air circulation mean that it is almost impossible for polar air masses to reach the tropics. Note the system of polar cells, Ferrel cells, and Hadley cells in each hemisphere. Polar air masses can penetrate into the temperate zone, but given wind flow patterns it would be very difficult to pass entirely through the temperate zone to enter tropical areas.
False. Cape Canaveral is at about 28[sup]o[/sup] 27’ N. St Augustine is at the 30[sup]o[/sup] line.
You are correct that Florida is not officially tropical, but you and the OP are both mistaken in re the location of the tropics. The tropic lines are at 23[sup]o[/sup] north and south, not 30[sup]o[/sup].
No part of Florida extends beyond the Tropic of Cancer. Key West sits around 24[sup]o[/sup] 30’ N.
To get cold temperatures far to the south, you need a large continental airmass over a large area. The best areas for this would be North America, and eastern Asia (China in particular). Anywhere in the southern Hemisphere is likely out, due to the large amount of water. Europe/western Russia can get brutally cold, but mountains generally block the cold air from getting too far south.
Southeast China seems to me to be the location with possibly the lowest temperatures, the farthest to the south. Strong high pressure over Mongolia/Siberia is common in the winter months, with these high pressure centers usually having some of the coldest temperatures on the planet. As these systems move east/southeast, they commonly develop gales across the East China/South China seas. Since southeast Asia is a bit farther south than the southeastern U.S., I think that this area would best meet your criteria.
Strong cold fronts can push southward through the central U.S. and western Gulf of Mexico, and due to the unique geography of the area, you can get quasi-cold frontal passages through southern Mexico (although due to airmass moderation of the Gulf of Mexico, these frontal passages are typically more wind shifts), and you can get gales through the Gulf of Tehuantepec in the Eastern Pacific (15-10 degrees north), due to strong high pressure building southward through the central U.S.
Ok, I was wrong about the edge of the Tropic of Cancer going to 30 degrees north latitude. I just figured the OP had it right. “Tropics” means within the Tropic of Cancer, or the Tropic of Capricorn. My point was, that only the western keys are anywhere near the edge of the Tropic of Cancer. ( it’s approximately one degree north of the northern edge of the Tropic of Cancer). Officially, it’s subtropical, but in reality the climate is tropical because of the effects of the surrounding Gulf of Mexico.
In no way was it 8F there in 1986. I was living there at the time of the Challenger disaster and the nighttime low fell to 26F, about 25F below normal for a nightly low in January. The 26F low temp is a record that still stands to this day.
I’ve lived in the area since 1970 (and still do) and the winter of 1986, perhaps because of the Challenger disaster, sticks out in my mind as the coldest. Many years we don’t even get a single frost here, let alone temps like we had that morning. The 25 year old coconut palm in my front yard can attest to what out typical winters are like.