Lamy Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lamy Ridge Observatory clear sky chart from 2005-11-06 to 2024-03-08.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	3 4 2 3 4 2 4 5% 6% 8% 60%	78756
	Night	4 4 2 4 4 2 4 4 5% 7% 60%	80862
Transparency	Day	21% 5% 9% 23% 27% 15%	78477
	Night	22% 5% 9% 23% 27% 14%	80663
Seeing	Day	7% 14% 28% 29% 17% 5%	14155
	Night	6% 7% 30% 38% 18% 2	24436

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	2 7% 3 4 3 2 3 4 6% 8% 59%	2765
	11th to 20th	Day	2 5% 2 3 3 1 2 3 4 6% 70%	2860
	21st to end	Day	3 5% 2 4 5% 3 5% 4 6% 7% 54%	3146
February	1st to 10th	Day	3 5% 2 5% 3 3 3 4 6% 7% 60%	1752
	11th to 20th	Day	3 5% 2 4 4 2 3 4 6% 7% 61%	1849
	21st to end	Day	3 6% 2 4 3 2 3 4 4 7% 63%	1570
March	1st to 10th	Day	3 4 1 3 4 3 5% 5% 6% 8% 59%	1944
	11th to 20th	Day	3 8% 3 5% 4 3 2 3 4 6% 60%	1980
	21st to end	Day	3 4 1 3 4 2 4 5% 5% 7% 61%	2260
April	1st to 10th	Day	3 2 1 2 3 2 5% 4 5% 7% 65%	2160
	11th to 20th	Day	3 4 2 4 4 2 4 5% 4 6% 62%	2131
	21st to end	Day	3 4 2 2 3 2 3 5% 5% 9% 63%	2160
May	1st to 10th	Day	3 2 2 3 3 2 4 4 5% 7% 66%	2160
	11th to 20th	Day	4 3 2 4 4 3 5% 4 6% 8% 58%	2214
	21st to end	Day	3 2 1 3 3 2 3 4 5% 8% 66%	2724
June	1st to 10th	Day	1 1 1 3 3 2 4 5% 8% 10% 62%	2520
	11th to 20th	Day	2 2 1 2 3 2 3 3 5% 5% 72%	2520
	21st to end	Day	5% 3 1 3 3 2 4 5% 7% 7% 59%	2520
July	1st to 10th	Day	3 3 2 5% 5% 5% 8% 7% 8% 10% 43%	2516
	11th to 20th	Day	3 3 2 4 5% 3 6% 7% 9% 11% 46%	2340
	21st to end	Day	4 3 2 5% 6% 4 9% 9% 9% 11% 37%	2545
August	1st to 10th	Day	3 3 2 4 6% 4 6% 7% 8% 11% 46%	2253
	11th to 20th	Day	4 3 1 4 4 4 6% 8% 9% 11% 46%	2123
	21st to end	Day	3 4 2 4 5% 3 7% 7% 8% 9% 48%	2376
September	1st to 10th	Day	6% 3 1 5% 5% 3 5% 6% 6% 9% 51%	2160
	11th to 20th	Day	5% 3 1 3 4 3 4 5% 6% 8% 58%	2160
	21st to end	Day	3 2 1 2 3 2 3 4 5% 7% 69%	1968
October	1st to 10th	Day	8% 4 2 4 3 3 4 4 5% 5% 59%	1800
	11th to 20th	Day	3 2 1 2 2 1 2 2 3 4 77%	1800
	21st to end	Day	4 3 1 3 2 1 2 2 4 4 73%	1980
November	1st to 10th	Day	2 2 1 2 2 1 2 4 4 8% 72%	1783
	11th to 20th	Day	2 3 1 2 2 2 3 4 4 7% 71%	1710
	21st to end	Day	4 5% 2 3 3 2 3 3 4 7% 63%	1710
December	1st to 10th	Day	2 5% 2 3 3 1 3 5% 5% 7% 64%	1577
	11th to 20th	Day	4 4 2 5% 5% 2 4 4 5% 8% 58%	1926
	21st to end	Day	4 5% 1 2 3 2 3 3 4 7% 66%	2794
January	1st to 10th	Night	2 6% 4 6% 5% 2 3 3 4 6% 58%	4219
	11th to 20th	Night	3 4 1 3 3 2 3 3 4 6% 67%	4110
	21st to end	Night	3 7% 2 4 4 2 4 5% 5% 8% 54%	4521
February	1st to 10th	Night	3 6% 3 4 3 2 3 2 4 6% 63%	2426
	11th to 20th	Night	5% 7% 2 3 3 2 3 4 5% 7% 60%	2218
	21st to end	Night	4 6% 2 3 3 2 3 4 4 5% 64%	1884
March	1st to 10th	Night	4 5% 1 4 3 2 4 4 5% 7% 62%	2171
	11th to 20th	Night	4 6% 3 4 4 2 3 4 5% 6% 59%	1980
	21st to end	Night	6% 4 2 4 3 2 3 4 4 5% 63%	2094
April	1st to 10th	Night	3 3 1 3 3 2 4 4 5% 7% 65%	1800
	11th to 20th	Night	3 5% 2 3 4 3 4 4 4 6% 62%	1777
	21st to end	Night	4 4 1 3 3 2 4 4 4 5% 67%	1800
May	1st to 10th	Night	3 4 1 3 4 2 3 4 4 7% 66%	1800
	11th to 20th	Night	5% 4 2 3 5% 3 5% 5% 5% 8% 54%	1675
	21st to end	Night	4 2 1 2 3 2 3 3 5% 7% 68%	1552
June	1st to 10th	Night	2 2 2 4 5% 2 5% 6% 6% 10% 57%	1440
	11th to 20th	Night	3 2 1 2 3 2 4 5% 4 8% 68%	1440
	21st to end	Night	4 3 1 3 5% 3 6% 7% 6% 8% 54%	1440
July	1st to 10th	Night	4 3 1 5% 7% 3 8% 6% 8% 10% 46%	1440
	11th to 20th	Night	2 4 2 4 6% 3 6% 8% 11% 13% 43%	1619
	21st to end	Night	5% 3 2 5% 5% 4 7% 9% 10% 14% 37%	1773
August	1st to 10th	Night	3 3 2 4 5% 4 7% 8% 10% 12% 42%	1686
	11th to 20th	Night	4 3 1 6% 6% 4 6% 8% 9% 13% 39%	1778
	21st to end	Night	3 2 1 4 5% 4 6% 7% 9% 12% 47%	1980
September	1st to 10th	Night	5% 3 1 3 5% 3 5% 7% 9% 10% 50%	1800
	11th to 20th	Night	5% 4 1 3 4 3 5% 5% 6% 8% 56%	1800
	21st to end	Night	4 3 1 3 3 2 3 4 4 6% 66%	1987
October	1st to 10th	Night	7% 4 2 3 3 2 4 4 4 5% 62%	2160
	11th to 20th	Night	4 2 1 2 2 2 2 2 3 5% 77%	2160
	21st to end	Night	4 2 1 2 3 1 2 3 4 6% 71%	2376
November	1st to 10th	Night	2 2 1 2 2 3 3 4 7% 74%	2274
	11th to 20th	Night	2 2 1 2 2 1 3 3 4 5% 74%	2470
	21st to end	Night	6% 5% 2 3 3 2 3 2 4 5% 64%	2470
December	1st to 10th	Night	4 4 2 3 3 2 3 3 4 7% 65%	2598
	11th to 20th	Night	4 4 2 3 4 2 5% 4 6% 8% 58%	3271
	21st to end	Night	4 6% 3 4 4 2 3 3 3 5% 63%	4873

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	21% 5% 7% 31% 30% 5%	2766
	11th to 20th	Day	17% 2 12% 38% 26% 5%	2860
	21st to end	Day	27% 6% 8% 23% 29% 6%	3146
February	1st to 10th	Day	22% 5% 9% 26% 28% 11%	1752
	11th to 20th	Day	22% 4 6% 28% 27% 14%	1859
	21st to end	Day	21% 4 3 20% 35% 17%	1570
March	1st to 10th	Day	21% 4 5% 23% 31% 17%	1944
	11th to 20th	Day	26% 4 6% 19% 32% 13%	1980
	21st to end	Day	22% 5% 6% 24% 31% 13%	2260
April	1st to 10th	Day	17% 5% 6% 21% 34% 18%	2160
	11th to 20th	Day	22% 5% 4 21% 30% 19%	2134
	21st to end	Day	18% 5% 6% 24% 33% 15%	2160
May	1st to 10th	Day	18% 4 5% 20% 33% 20%	2160
	11th to 20th	Day	24% 6% 9% 21% 26% 15%	2217
	21st to end	Day	17% 5% 9% 19% 25% 26%	2724
June	1st to 10th	Day	15% 6% 11% 22% 25% 22%	2520
	11th to 20th	Day	14% 5% 4 14% 24% 39%	2520
	21st to end	Day	22% 6% 8% 19% 23% 22%	2520
July	1st to 10th	Day	30% 9% 14% 15% 17% 14%	2447
	11th to 20th	Day	24% 9% 17% 25% 16% 8%	2271
	21st to end	Day	32% 11% 21% 26% 9% 1	2404
August	1st to 10th	Day	27% 10% 20% 21% 14% 9%	2238
	11th to 20th	Day	26% 10% 15% 23% 18% 8%	2123
	21st to end	Day	27% 9% 13% 24% 22% 5%	2376
September	1st to 10th	Day	26% 8% 10% 23% 22% 10%	2160
	11th to 20th	Day	22% 6% 9% 19% 24% 18%	2160
	21st to end	Day	15% 4 5% 24% 34% 18%	1968
October	1st to 10th	Day	26% 6% 6% 20% 25% 18%	1800
	11th to 20th	Day	14% 2 4 16% 36% 30%	1800
	21st to end	Day	16% 3 6% 21% 37% 17%	1980
November	1st to 10th	Day	12% 3 5% 22% 41% 17%	1783
	11th to 20th	Day	14% 3 6% 26% 38% 12%	1710
	21st to end	Day	22% 4 4 20% 33% 17%	1710
December	1st to 10th	Day	18% 4 10% 33% 24% 10%	1577
	11th to 20th	Day	26% 3 9% 22% 29% 11%	1924
	21st to end	Day	19% 4 8% 21% 33% 15%	2794
January	1st to 10th	Night	27% 5% 8% 26% 26% 8%	4219
	11th to 20th	Night	18% 4 9% 36% 25% 8%	4110
	21st to end	Night	27% 5% 10% 24% 28% 7%	4521
February	1st to 10th	Night	22% 4 9% 25% 27% 12%	2426
	11th to 20th	Night	24% 4 6% 26% 26% 14%	2218
	21st to end	Night	21% 3 4 17% 35% 20%	1884
March	1st to 10th	Night	21% 4 4 24% 30% 16%	2171
	11th to 20th	Night	25% 4 6% 22% 31% 12%	1980
	21st to end	Night	23% 4 6% 20% 34% 13%	2094
April	1st to 10th	Night	18% 4 6% 23% 30% 19%	1800
	11th to 20th	Night	22% 4 6% 21% 27% 20%	1777
	21st to end	Night	20% 4 8% 21% 34% 14%	1800
May	1st to 10th	Night	20% 3 8% 17% 32% 20%	1800
	11th to 20th	Night	27% 6% 12% 20% 20% 16%	1676
	21st to end	Night	16% 5% 11% 20% 22% 26%	1552
June	1st to 10th	Night	22% 6% 15% 19% 18% 20%	1440
	11th to 20th	Night	16% 4 5% 16% 22% 37%	1440
	21st to end	Night	25% 9% 11% 17% 17% 22%	1440
July	1st to 10th	Night	31% 10% 14% 19% 13% 13%	1400
	11th to 20th	Night	26% 10% 22% 21% 13% 7%	1566
	21st to end	Night	32% 11% 29% 19% 7% 1	1674
August	1st to 10th	Night	28% 11% 22% 18% 11% 8%	1677
	11th to 20th	Night	30% 11% 20% 20% 13% 6%	1778
	21st to end	Night	24% 8% 18% 28% 15% 7%	1980
September	1st to 10th	Night	25% 6% 19% 24% 18% 9%	1800
	11th to 20th	Night	24% 7% 12% 18% 22% 17%	1800
	21st to end	Night	19% 4 8% 20% 31% 18%	1987
October	1st to 10th	Night	24% 5% 8% 21% 21% 21%	2160
	11th to 20th	Night	12% 2 4 16% 36% 29%	2160
	21st to end	Night	15% 3 5% 22% 36% 18%	2376
November	1st to 10th	Night	12% 2 5% 24% 40% 17%	2274
	11th to 20th	Night	13% 3 5% 25% 40% 14%	2470
	21st to end	Night	24% 3 5% 20% 32% 17%	2470
December	1st to 10th	Night	20% 4 8% 32% 28% 9%	2598
	11th to 20th	Night	24% 4 9% 24% 30% 10%	3272
	21st to end	Night	24% 4 7% 22% 30% 12%	4873

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	9% 19% 39% 25% 7% 1	270
	11th to 20th	Day	14% 20% 37% 20% 9%	270
	21st to end	Day	4 19% 38% 24% 13% 2	297
February	1st to 10th	Day	7% 25% 39% 23% 6% 1	270
	11th to 20th	Day	7% 26% 40% 20% 6%	270
	21st to end	Day	13% 31% 35% 18% 3	225
March	1st to 10th	Day	10% 24% 32% 27% 7%	335
	11th to 20th	Day	13% 25% 30% 22% 8% 1	420
	21st to end	Day	14% 29% 34% 17% 5% 1	462
April	1st to 10th	Day	8% 28% 36% 21% 5% 1	420
	11th to 20th	Day	12% 28% 36% 16% 7% 1	412
	21st to end	Day	11% 26% 38% 21% 3 1	420
May	1st to 10th	Day	6% 24% 43% 22% 5% 1	423
	11th to 20th	Day	7% 15% 35% 28% 13% 2	501
	21st to end	Day	5% 11% 33% 37% 11% 2	679
June	1st to 10th	Day	3 6% 23% 42% 23% 3	630
	11th to 20th	Day	4 7% 25% 36% 25% 3	630
	21st to end	Day	6% 6% 22% 33% 27% 6%	630
July	1st to 10th	Day	4 3 12% 37% 36% 9%	617
	11th to 20th	Day	3 3 7% 34% 35% 18%	444
	21st to end	Day	2 1 7% 28% 41% 20%	487
August	1st to 10th	Day	3 3 12% 37% 35% 11%	447
	11th to 20th	Day	4 2 16% 41% 28% 9%	437
	21st to end	Day	5% 3 12% 38% 33% 10%	495
September	1st to 10th	Day	6% 2 17% 40% 26% 8%	450
	11th to 20th	Day	5% 4 27% 37% 21% 7%	450
	21st to end	Day	6% 6% 30% 31% 19% 9%	280
October	1st to 10th	Day	9% 12% 29% 24% 21% 4	270
	11th to 20th	Day	9% 13% 31% 28% 15% 4	270
	21st to end	Day	11% 12% 32% 27% 15% 3	297
November	1st to 10th	Day	7% 18% 41% 23% 11% 1	270
	11th to 20th	Day	4 13% 38% 28% 16% 1	270
	21st to end	Day	10% 22% 30% 26% 10% 3	270
December	1st to 10th	Day	9% 18% 38% 26% 8% 1	270
	11th to 20th	Day	7% 19% 41% 27% 6%	270
	21st to end	Day	12% 27% 34% 22% 4 1	297
January	1st to 10th	Night	5% 8% 37% 35% 13% 1	830
	11th to 20th	Night	6% 6% 38% 37% 11% 2	760
	21st to end	Night	7% 8% 36% 36% 11% 2	836
February	1st to 10th	Night	6% 9% 40% 36% 8% 1	760
	11th to 20th	Night	8% 10% 42% 31% 8%	744
	21st to end	Night	10% 10% 50% 28% 3	628
March	1st to 10th	Night	6% 11% 41% 33% 8% 1	750
	11th to 20th	Night	7% 11% 32% 38% 12%	720
	21st to end	Night	7% 12% 37% 38% 6%	708
April	1st to 10th	Night	4 15% 44% 30% 7%	540
	11th to 20th	Night	7% 14% 35% 35% 9%	533
	21st to end	Night	7% 13% 39% 34% 7% 1	540
May	1st to 10th	Night	3 9% 38% 38% 12%	540
	11th to 20th	Night	8% 7% 30% 36% 17% 2	531
	21st to end	Night	5% 8% 34% 41% 12% 1	584
June	1st to 10th	Night	4 4 25% 45% 21% 1	540
	11th to 20th	Night	3 2 27% 50% 17% 1	540
	21st to end	Night	5% 3 20% 44% 27% 1	540
July	1st to 10th	Night	4 2 7% 45% 38% 4	525
	11th to 20th	Night	3 1 7% 34% 51% 5%	522
	21st to end	Night	6% 2 5% 27% 54% 7%	591
August	1st to 10th	Night	5% 2 7% 29% 47% 10%	537
	11th to 20th	Night	3 3 9% 38% 41% 5%	534
	21st to end	Night	3 1 6% 42% 41% 6%	594
September	1st to 10th	Night	6% 1 9% 47% 33% 4	540
	11th to 20th	Night	6% 2 12% 46% 31% 2	540
	21st to end	Night	6% 5% 21% 44% 21% 3	558
October	1st to 10th	Night	8% 4 21% 47% 20% 1	720
	11th to 20th	Night	5% 5% 29% 43% 16% 3	720
	21st to end	Night	5% 7% 28% 36% 20% 4	792
November	1st to 10th	Night	4 4 32% 40% 17% 2	794
	11th to 20th	Night	3 7% 32% 40% 15% 2	950
	21st to end	Night	8% 8% 32% 36% 14% 3	950
December	1st to 10th	Night	7% 9% 38% 35% 10% 1	950
	11th to 20th	Night	7% 9% 38% 36% 9% 1	950
	21st to end	Night	9% 10% 42% 33% 7%	1045

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