Summers in California it seemed that midday was really hot and then after about 3pm the worst of the heat was over for the night. Now that I’m in Oregon I’ve noticed that it’s much hotter on my way home from work than it was during my lunch hour. Is this a latitude thing? Something else? My imagination? Any meteorologists in the house want to help me understand the weather?
That isn’t true on the East Coast and I don’t think it is true anywhere but I would be happy to see if I am wrong. Peak temperature is usually reached between 1 and 3 pm unless there is a warm front moving in.
It is easy to verify this for your location on any given day. Both www.weather.com and www.wunderground.com give detailed temperature measurements by the hour if you drill down based on your zip code. They also note peak temperature times for each day.
This is generally true in any locale.
Even though the Sun is directly overhead at mid-day, and is most intense then, the temperature continues to rise during the afternoon, as the Sun continues to pump energy into the Earth. Think about an oven - if you set it for “Full on” for 5 minutes, and then backed the setting down until it was 50% on for two more hours, the temperature would be much higher at the end of the two hours than it was at the end of the first 5 minutes.
Seems like temps have been maxing out around 1700 or so. (I’ll try to pay attention to the weather news in the morning.) I’m at a higher latitude than the OP.
It just depends on the weather, location, and time of year. The temperature isn’t highly dependent on the time of day. The ground temperature changes through the day, usually getting hotter as the day goes on. The air temperature may be more affected by a moving air mass than the amount of local sunshine. Humidity can vary through the day, and greater humidity gives the feel of warmer temperatures. Also, as noted above, peak temperature is usually reached sometime in the afternoon, so if you’re only outside during lunchtime, and not again until the evening, you may not be noticing how much hotter it was in between. There are an awful lot of factors involved in local temperature.
Holy crap, where do you live?!? The planet Mercury???
5:00 pm.
I wanted to say you were wrong based on the several places I have lived but I looked up hourly temperature data for several random places quite far apart and the temperature really does seem to climb higher later in the afternoon in Oregon and not in the others. That isn’t true in most places I am familiar with. New England is at roughly the same latitude as Oregon and it isn’t true here. Peak temperatures generally happen during midday instead of late afternoon. There may be some time zone factors involved because New England is right on the border of the Eastern Time Zone but that still doesn’t account for all of it.
Here is the temperature chart by hour for Eugene, OR for tomorrow:
http://www.weather.com/weather/hourbyhour/graph/Eugene+OR+USOR0118:1:US?pagenum=2&nextbeginIndex=6
on the west coast there are mountains which block wind flow. this might both keep some heat from being blown away. also the mountains capture heat which might be given up during the late afternoon.
lots of weather can happen regionally and in micro climates.
It’s weird, right? 81 degrees at 1pm, and then 88 at 5pm. That’s quite a change for the second half of the afternoon.
Similarly in Sacramento, which is in a valley with mountains to the east, peak temperatures are usually between 4 and 5 pm.
Seattle: http://www.weather.com/weather/hourbyhour/graph/Seattle+WA+USWA0395:1:US?pagenum=2&nextbeginIndex=6
Blaine: http://www.weather.com/weather/hourbyhour/graph/Blaine+WA+98230:4:US?pagenum=2&nextbeginIndex=6
Yesterday in Sacramento: http://www.weather.com/weather/yesterday/hourly/Sacramento+CA+95823:4:US
I read it as an indictment of global warming since temps hadn’t increased for 300 years.
This is actually an important to lesson to learn about all kinds of events. It’s covered in trig (sin, cos, and tan) and then again in calculus, but most people don’t see the application to the real world.
If you graph the value you’re tracking along with the rate of change in that value, what you see with equations that are sine-like (and temperature is one of those things) is that the highest rate of change comes at the middle range of the value. (In weather terms: at noon, you’re heating up the fastest, but you’re not at the hottest value.) At the peak value, the rate of change is actually zero (in the evening, you’ve hit your highest temperature, but the sun is already on its way down and the temperature is not increasing any more).
I was hoping to find something good to link to on this, but either my Google-fu is weak or I’ve forgotten enough math to remember the right terms to search for.
The same relationship applies to the temperatures of the seasons. And to a lot of financial and economic data, such as unemployment and GDP growth… which is why people are always investing at the wrong time and why public perception about the economy is always wrong (or, at least, always trailing what the economy is actually doing).
May I point out the obvious answer? 
When you’re going home from work you’re in a small metal box, possibly stuffed with other fat sweaty people if you take public transportation, which in Portland usually have poor or no air conditioning.
… that aside, the actual air temperature does peak before 3:00 usually, but the temperature in a structure with no air conditioning will peak later because of the heat absorption lag time. (On the other hand, it’ll be cooler for longer in the morning also.)
The phenomenon is called Hysteresis.
Not to sound too simple-minded, but by the time you’re going home in the late afternoon/early evening (I presume, and that it’s during the summer), it’s that the sun’s been up for longer by then and has had more time to heat things up. I live in the Seattle area and it’s really noticeable here because our summer days are so long–16 hours–and our winter days are excruciatingly short–the shortest day of the year has about 8 hours of when the sun is over the horizon.
Very good, John! That too.
As mentioned previously, I live in the Seattle area which is squeezed in between the Olympic mountains to the west, out on the Olympic Peninsula, and the glorious Cascade Range to the east. Because of the topography and other factors, it can make weather forecasting very difficult, not like it is when you’re in pancake-flat Midwest.
Here’s my take: if when you lived in California you lived on the coast, as most people here do, you were experiencing the afternoon on-shore flow of air (from the ocean to the land) which is very typical in the afternoon in a marine climate, even a warm one. This cools down the afternoon with cooler marine air.
If, in Oregon, you live in the Willamette Valley, as most people do, this on-shore flow is interrupted by the Coast Range. Therefore, the heat builds all afternoon without anything to blow it away or cool it down until it cools itself down during the night.
I have lived in both climates, and I know exactly what you mean. Here in San Francisco, downtown will often be sunny and warm(ish) at lunchtime, and cloudy and cool by the time I am ready to go home. I grew up in Portland, leaving when I was 30, and during warm weather (rare as that seemed overall) it was always warmest in the late afternoon and early evening.
Roddy