TheClimateChanger

Morning thoughts:

Well, I'd personally say a negative number for (2) and suggest the UHI effect has had cooling trend on the winter averages, considering the US CRN stations [all sited in pristine rural locations] show more, not less, warming since 2005 than the full network.

Ten coldest summers at Detroit (by average hourly real feel) (1934-present) 1992 66.8 1985 68.0 1972 68.4 1965 68.4 1964 68.5 1979 68.6 1982 68.7 1962 68.8 1967 69.0 2009 69.4 Ten hottest summers at Detroit (by average hourly real feel) (1934-present) 1995 75.6 2005 75.4 1955 75.3 2012 75.2 2016 75.2 2010 75.0 2018 75.0 1988 75.0 2011 75.0 1949 74.7

Ten coldest summers at Detroit (by average daily mean temperature) (1934-present) 1992 66.9 1985 67.7 1972 68.1 1982 68.1 1979 68.3 1967 68.9 1958 69.1 2004 69.1 1945 69.2 2009 69.3 Ten warmest summers at Detroit (by average daily mean temperature) (1934-present) 2016 74.9 2005 74.8 2012 74.7 1995 74.5 1955 74.4 2010 74.4 2011 74.4 2018 74.4 1988 74.2 2021 74.2

Ten coldest summers at Detroit (by average hourly observation) (1934-present) 1992 66.7 1985 68.0 1972 68.0 1964 68.2 1979 68.3 1965 68.3 1982 68.4 1962 68.6 1967 68.8 2004 69.0 Ten hottest summers at Detroit (by average hourly temperature) (1934-present) 2012 74.8 2005 74.6 2016 74.6 1955 74.5 1988 74.4 2018 74.3 2010 74.2 1995 74.2 2020 74.1 2011 74.1

Ten least humid summers at Detroit (1934-present) 1936 55.7 1985 56.6 1992 56.7 1965 56.7 1950 57.0 1946 57.1 1934 57.1 1958 57.4 1971 57.6 1964 57.8 Ten most humid summers at Detroit (1934-present) 1995 64.4 2010 63.2 2021 63.2 1998 63.0 1949 62.8 2002 62.7 1987 62.6 1973 62.5 1993 62.5 2005 62.5

I don't know how this myth keeps coming up. Recent summers have been hotter and more humid at Detroit. This is objective data, not opinion. Note data discontinuity in 1959 is responsible for much of the cooling in the 1960s and 1970s. Data for 1934-1958 from City Airport, and from Metropolitan Wayne International Airport since 1959. Data source for all hourly readings is Iowa Environmental Mesonet, and for the mean average temperatures is xMacis.

Not liking all of this heavy rainfall language just about every day. They must be getting nervous from all the recent 1000-year floods. Today Considerable cloudiness. Areas of fog this morning. Isolated showers and thunderstorms this afternoon. Some thunderstorms may produce heavy rainfall this afternoon. Highs in the mid 80s. West winds around 5 mph. Chance of rain 20 percent. Tonight Mostly cloudy. Isolated showers and thunderstorms in the evening. Patchy fog after midnight. Some thunderstorms may produce heavy rainfall in the evening. Humid with lows in the mid 60s. Southeast winds around 5 mph, becoming south after midnight. Chance of rain 20 percent. Thursday Partly sunny. Patchy fog in the morning. Isolated showers in the morning, then scattered showers and thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the afternoon. Humid with highs in the mid 80s. Southwest winds around 5 mph. Chance of rain 50 percent. Thursday Night Mostly cloudy with scattered showers and thunderstorms in the evening, then partly cloudy after midnight. Areas of fog after midnight. Some thunderstorms may produce heavy rainfall in the evening. Humid with lows in the upper 60s. West winds around 5 mph in the evening, becoming light and variable. Chance of rain 50 percent. Friday Partly sunny. Areas of fog in the morning. Scattered showers and thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the afternoon. Humid with highs in the mid 80s. Light and variable winds, becoming west around 5 mph in the afternoon. Chance of rain 30 percent. Friday Night Mostly cloudy with scattered showers and thunderstorms in the evening, then mainly clear after midnight. Some thunderstorms may produce heavy rainfall in the evening. Lows in the upper 60s. Chance of rain 30 percent. Saturday Mostly sunny. Highs in the upper 80s. Heat index values in the mid 90s in the afternoon. Saturday Night Mostly cloudy with scattered showers and thunderstorms. Some thunderstorms may produce heavy rainfall. Lows around 70. Chance of rain 40 percent. Sunday Partly sunny with scattered showers in the morning, then mostly cloudy with numerous showers and scattered thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the afternoon. Highs in the upper 80s. Chance of rain 70 percent. Sunday Night Mostly cloudy in the evening, then becoming partly cloudy. Scattered thunderstorms. Numerous showers, mainly in the evening. Some thunderstorms may produce heavy rainfall. Lows in the upper 60s. Chance of rain 70 percent. Monday Partly cloudy. Scattered showers in the afternoon. Highs in the upper 80s. Chance of rain 30 percent. Monday Night Scattered showers in the evening. Mainly clear. Lows in the upper 60s. Chance of rain 30 percent. Tuesday Partly cloudy. Scattered showers and thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the afternoon. Highs in the upper 80s. Chance of rain 40 percent.

Not even close. Low was 66F.

I always see people dismiss this analysis and go back to 1895, but that makes little sense. From 1895 to 1970, CO2 went from 294 to 324 ppm, a relatively small 30 ppm increase over 75 years. It's now more than 100 ppm higher than it was 55 years ago. So that's a big change, and there's less cooling sulfur aerosols from industry today. There's certainly nothing to suggest the trendline is going to get less steep with time. In fact, 4 of the past 6 Januarys are above the trend I display above, whereas 6 of the first 7 and 8 of the first 10 are below. This suggests a possible acceleration in the trendline.

I think such warming is plausible, especially in the winter. Last 50 years trend is +12.3F/century statewide for January - more in certain areas, especially in the north. Prior to this year's chilly January, it had been nearing 14F/century. If we reel off a couple of very mild Januarys, it could reach 15F/century soon.

A little deeper dive in the Chester County temperatures over the past 18 years. Maybe @chubbshas an explanation. I calculate a warming trend of 12.64F/century at the U.S. CRN station located at Avondale 2N, a warming trend of 12.13F/century at PHL Airport, a warming trend of 11.14F/century at @ChescoWx's East Nantmeal location. Yet NCEI only reports a warming of 7.99F/century. According to data supplied by @ChescoWx, other stations he analyzes (varying sites) show a warming of 6.91F/century over this timeframe when averaged together. It looks to me like NCEI is underdoing recent warming, when the gold standard CRN station is showing so much warming, supported by PHL's data and @ChescoWx's high quality backyard data. I suspect actual warming could reach 15-20F/century over the coming decades before plateauing.

Thank you! I wouldn't say that's an insignificant difference, no? The two highest quality stations (Avondale and East Nantmeal) with data available over the entire period show a warming trend of 12.64F/century and 11.14F/century respectively over that time frame, while the others show a warming trend of 6.91F/century. That's nearly half as much warming. Chester County is very fortunate to have a USCRN station. With the official ChescoWx (TM) index deviating so much from the CRN data [especially when it's largely corroborated by your own temperature data] just over the past 18 years, isn't that a concern?

Can you post the mean temperatures for each year as in the original graphic for EN and Avondale?

Well, can we see it? This would be a good test of the validity of the official ChescoWx temperature index over the past couple of decades. We'd have a USCRN station, your own gold standard East Nantmeal data, and then the official ChescoWx county-wide average for 2007-2024.

Can you do an overlay of these two stations, plus your full Chester County dataset over the same timeframe (2007-present)?

I can give you a clue. The period before 1970 was the twilight of relative climate stability. CO2 levels rose about 30 ppm between 1895 & 1969. They have risen another 100 ppm since then.

Several of those threaded records have large jumps in elevation, and many go from city center to suburban even rural. With even the stations outside of the bigger cities having significant biases. Regardless, again, you feel the need to interject with "context" unrelated to my original post. Here is the full Ohio dataset for January. There is a small cooling trend from 1895-1969 of about 0.5F/century. Since 1970, it's warming at a rate of 10.1F/century, and even higher than that in the northern parts of the state. Grafted together, yes, it looks like there's not much trend. But what do you think is more relevant to determining trend over the coming decades - the most recent 5 1/2 decades, or data from the 1800s?

Makes sense. It's not well sited, so it probably has a seasonal bias. MADIS does not have a good way to describe a cool bias, because typically the bias is warm. Funny too, his average error is higher over the past 28 days, even though only the Coatesville site is flagged due to the high standard deviation.

More misleading nonsense. Regarding the Tokyo data, you know something’s up when there’s a graph from Tony Heller’s wife limited to 1994-2021. You can pull up the raw data for Tokyo from JMA. There is, in fact, an inhomogeneity flagged in December 2014, consistent with the inflection point in this small subset of data. So the bias correction appears to be correct. Moreover, the long-term trend is actually greatly reduced by the UHI correction. That’s why nothing before 1994 is shown there. Further, the two warmest years in the raw data are the last two years (even without correcting for the change that occurred in 2014). 2025 appears well on its way to approaching those highs. Feel free to look for yourself: https://www.data.jma.go.jp/stats/data/en/index.html

While there hasn’t been any temps of 95 or higher, every day since June 21 has been above normal, with only 2 days below normal since June 4. That trend looks to continue for at least the next couple of weeks.

Looks like it rebounded to a daily high of 93. Probably just a result of variable cloud cover.

Funnily enough, the USCRN data largely supports my contention decades ago that the US climate record likely understates the change. If you accept USCRN as the gold standard, then, you must conclude nClimDiv [and the older USHCN] clearly understates warming in recent decades.

I do want to clarify one thing. I indicated USCRN has a slightly larger warming trend than nClimDiv over the period. I think that actually understates the difference. While the trend difference over the 21 years of overlap are relatively small, the magnitude of the trend is quite larger in USCRN. You can see Zeke Hausfather addressed this in 2023, after some images purporting to show minimal change in USCRN were shared on Twitter/X and picked up some steam. In reality, there was a large trend in the data masked by the much greater month-to-month variability in the data. The most accurate record of US temperatures shows rapid warming At that time, per Hausfather, the trends were 0.3C/decade for USCRN and 0.23C/decade for nClimDiv. Revisiting this with data updated through the first half of 2025, the difference has become a bit more substantial. Obviously, 2025 is incomplete, so these trends could be off a bit if the final annual anomaly deviates significantly. But I calculate the trend in USCRN at 0.47F/decade, or 4.7F/century, while nClimDiv is 0.34F/decade, or 3.4F/century. Note, I use degrees Fahrenheit, as opposed to degrees Celsius as Zeke did.