30 F in July at a Southern California coastal location? (climate, recorded, temperatures)

[ABrandNewWorld]

I was checking the weather records for Laguna Niguel, California and something seems way off. It claims that July has a record low of 30 F set on July 13, 1978 and the night prior was 32 F. It's fairly unusual for it to get that cold in the middle of winter, let alone in the heart of July. Their nights are cooler than many nearby microclimates but it still seems absurd. (elevation is about 400 feet ASL).

I find this record hard to believe and think there was an error in recording or reporting. The SST would normally be in upper 60s that time of the year but could go as low as upper 50s if it's a La Nina year. How could the adjacent land (even slightly up in the hills) get that cold in mid-summer? Daylight hours are near its longest as well so it would have fewer cooling hours than in winter. Can someone help me with this?

Both intellicast and weather.com hold to this July record:
Intellicast - Local Weather Forecast, Reports and Maps
Average Weather for Laguna Niguel, CA - Temperature and Precipitation (click on record low).

[nei]

here's the station (don't trust weather.com as much):

LAGUNA BEACH, CALIFORNIA - Climate Summary

LAGUNA BEACH, CALIFORNIA Period of Record Daily Climate Summary

[tommyFL]

Not very likely. Look at the difference between these two. There's also some missing data when the record low was apparently set.

[nei]

the 38°F on the 7th is still impressive, but it's odd why it's so different from Newport Beach.

[tommyFL]

Originally Posted by nei

the 38°F on the 7th is still impressive, but it's odd why it's so different from Newport Beach.

I'm thinking it's an error.

[Cambium]

Originally Posted by ABrandNewWorld

I was checking the weather records for Laguna Niguel, California and something seems way off. It claims that July has a record low of 30 F set on July 13, 1978 and the night prior was 32 F. It's fairly unusual for it to get that cold in the middle of winter, let alone in the heart of July. Their nights are cooler than many nearby microclimates but it still seems absurd. (elevation is about 400 feet ASL).

I find this record hard to believe and think there was an error in recording or reporting. The SST would normally be in upper 60s that time of the year but could go as low as upper 50s if it's a La Nina year. How could the adjacent land (even slightly up in the hills) get that cold in mid-summer? Daylight hours are near its longest as well so it would have fewer cooling hours than in winter. Can someone help me with this?

Both intellicast and weather.com hold to this July record:
Intellicast - Local Weather Forecast, Reports and Maps
Average Weather for Laguna Niguel, CA - Temperature and Precipitation (click on record low).

Yeah, that would be impressive, if was true..

Your first link goes to the general page not where you saw the record.

The second link is easy. The reading was an error and it got marked down automatically and plotted onto the map as you saw. Sources like those you listed DO NOT go back and fix erroneous readings that stations sometimes produce. They also DO NOT get fixed after quality control fixes them days later.

As Tommy showed, NOAA did the right thing and used "Missing" data since it was an error reading and they don't know what the actual low was that day.

Sometimes if it doesn't make sense it's not real, or you can just check the official sites with NCDC and NOAA!

That 38 is believable and when they did quality control they must of found it was good to leave it at that. But 30F? No.

Here are the maps from that week. Looks like a trough was cut out and a cut off low was around so cold air was available.

http://docs.lib.noaa.gov/rescue/dwm/...-19780716.djvu

[SoCal Midwest Noobie]

I cant speak for Laguna Niguel, but where I lived in the IE, I remember running heat in July 2000. And a few cold July evenings as late as 2010. It does happen. 30 does seem a bit much though.

[unobtainium]

It has to be an error. I don't think it's physically possible. Where would that cold air even come from in the middle of July? Nowhere else on the Pacific coast has recorded freezing temperatures in July and August. Seattle's record for July is 46. Vancouver: 44. Portland: 43. San Francisco: 47.

[tarzan_taborda]

It's seems too low to me, I would in a 40 F, or a very localized 35/37 F, but 30 just seems impossible.

It's a 34ºN latitude we're talking about.

[Marv101]

The record low for that date at John Wayne Airport 21 miles away is 62 degrees, and for downtown LA (City Hall) is 54 degrees, so those numbers are way off.