Luling Skies Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Luling Skies Observatory clear sky chart from 2005-11-06 to 2024-02-20.

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	11% 6% 3 6% 6% 4 6% 6% 6% 8% 38%	79005
	Night	10% 5% 2 5% 5% 3 4 5% 6% 8% 47%	80141
Transparency	Day	41% 8% 12% 17% 16% 5%	78742
	Night	34% 7% 13% 20% 18% 8%	79924
Seeing	Day	11% 5% 17% 24% 26% 18%	13643
	Night	12% 4 18% 31% 27% 8%	23405

By Month

Percentage Cloud Cover SE (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	15% 6% 3 6% 6% 4 5% 5% 6% 9% 37%	2847
	11th to 20th	Day	11% 5% 3 4 4 2 4 4 4 6% 53%	2886
	21st to end	Day	23% 8% 3 6% 5% 3 4 4 4 6% 33%	3476
February	1st to 10th	Day	14% 9% 3 6% 5% 3 5% 5% 5% 7% 37%	1900
	11th to 20th	Day	15% 8% 2 6% 4 2 4 4 5% 8% 43%	1838
	21st to end	Day	16% 8% 3 7% 5% 4 5% 4 5% 7% 36%	1480
March	1st to 10th	Day	12% 7% 3 6% 7% 4 5% 5% 5% 7% 39%	1914
	11th to 20th	Day	13% 6% 3 7% 6% 3 4 5% 6% 9% 38%	1980
	21st to end	Day	11% 6% 2 4 4 3 5% 5% 5% 8% 48%	2268
April	1st to 10th	Day	9% 5% 2 5% 6% 4 6% 6% 6% 8% 43%	2160
	11th to 20th	Day	13% 5% 3 6% 6% 4 5% 5% 6% 10% 39%	2134
	21st to end	Day	8% 4 3 5% 5% 4 5% 5% 5% 9% 47%	2160
May	1st to 10th	Day	8% 4 2 5% 5% 3 6% 5% 6% 10% 45%	2160
	11th to 20th	Day	8% 5% 2 5% 6% 4 6% 6% 8% 9% 42%	2124
	21st to end	Day	7% 4 3 6% 8% 5% 7% 6% 6% 10% 37%	2337
June	1st to 10th	Day	9% 6% 3 9% 8% 4 8% 8% 7% 10% 28%	2160
	11th to 20th	Day	5% 4 3 7% 8% 5% 10% 8% 9% 12% 29%	2277
	21st to end	Day	6% 7% 4 8% 10% 7% 8% 11% 8% 10% 22%	2340
July	1st to 10th	Day	10% 8% 4 8% 8% 6% 9% 8% 9% 9% 20%	2340
	11th to 20th	Day	9% 6% 4 8% 10% 6% 9% 10% 9% 10% 20%	2296
	21st to end	Day	8% 6% 3 7% 9% 5% 10% 8% 10% 8% 24%	2350
August	1st to 10th	Day	6% 5% 4 8% 8% 5% 8% 9% 11% 11% 25%	2148
	11th to 20th	Day	9% 8% 4 8% 9% 6% 8% 8% 8% 10% 22%	2125
	21st to end	Day	10% 7% 3 8% 8% 4 7% 7% 8% 9% 29%	2376
September	1st to 10th	Day	10% 6% 3 7% 8% 5% 8% 7% 7% 9% 30%	2160
	11th to 20th	Day	10% 6% 3 7% 7% 4 6% 7% 7% 8% 34%	2116
	21st to end	Day	8% 4 3 6% 6% 4 5% 6% 6% 7% 44%	1980
October	1st to 10th	Day	7% 3 2 5% 6% 3 5% 5% 5% 8% 51%	1886
	11th to 20th	Day	7% 4 2 5% 5% 3 4 4 6% 8% 51%	1800
	21st to end	Day	10% 4 2 5% 4 3 4 4 5% 7% 52%	1980
November	1st to 10th	Day	7% 4 1 5% 4 3 4 6% 5% 7% 53%	1858
	11th to 20th	Day	10% 6% 2 4 5% 2 4 3 4 7% 53%	1900
	21st to end	Day	12% 6% 3 6% 5% 3 4 6% 6% 7% 43%	1723
December	1st to 10th	Day	13% 5% 3 5% 5% 3 5% 5% 6% 7% 43%	1710
	11th to 20th	Day	15% 9% 3 7% 6% 3 3 5% 4 6% 39%	2344
	21st to end	Day	17% 8% 3 6% 6% 3 4 5% 5% 6% 38%	3472
January	1st to 10th	Night	15% 9% 2 5% 4 3 4 5% 4 6% 43%	4088
	11th to 20th	Night	14% 5% 2 3 4 2 3 3 4 6% 52%	4059
	21st to end	Night	24% 7% 2 4 4 2 3 3 4 7% 39%	4180
February	1st to 10th	Night	15% 6% 3 6% 5% 3 4 4 5% 7% 43%	2280
	11th to 20th	Night	17% 7% 3 4 4 2 3 4 5% 7% 44%	2213
	21st to end	Night	17% 7% 3 5% 5% 3 4 4 5% 7% 40%	1776
March	1st to 10th	Night	12% 6% 3 6% 5% 2 4 5% 5% 7% 46%	2060
	11th to 20th	Night	12% 6% 2 5% 5% 3 5% 6% 7% 8% 42%	1980
	21st to end	Night	9% 5% 2 4 5% 2 4 4 5% 7% 53%	2088
April	1st to 10th	Night	13% 5% 2 5% 4 2 5% 5% 5% 7% 47%	1800
	11th to 20th	Night	11% 5% 2 5% 5% 3 5% 4 5% 7% 47%	1775
	21st to end	Night	5% 4 2 4 4 3 5% 5% 6% 8% 54%	1800
May	1st to 10th	Night	8% 3 2 3 3 3 4 4 6% 11% 54%	1800
	11th to 20th	Night	6% 4 2 6% 5% 4 5% 6% 6% 10% 48%	1769
	21st to end	Night	6% 3 2 4 4 3 5% 5% 7% 10% 50%	1938
June	1st to 10th	Night	7% 4 2 5% 4 4 5% 6% 7% 12% 44%	1800
	11th to 20th	Night	3 4 2 4 5% 3 5% 6% 9% 12% 48%	1674
	21st to end	Night	6% 5% 2 5% 4 3 5% 6% 8% 12% 43%	1620
July	1st to 10th	Night	5% 5% 3 4 5% 4 7% 6% 8% 13% 41%	1620
	11th to 20th	Night	4 3 2 4 5% 3 6% 7% 10% 16% 40%	1660
	21st to end	Night	3 4 3 5% 6% 4 6% 7% 8% 13% 43%	1968
August	1st to 10th	Night	2 2 1 4 5% 3 5% 6% 8% 14% 51%	1790
	11th to 20th	Night	5% 3 2 6% 6% 3 6% 8% 10% 14% 36%	1776
	21st to end	Night	7% 5% 2 5% 5% 3 6% 6% 7% 10% 43%	1980
September	1st to 10th	Night	6% 5% 2 5% 6% 4 6% 7% 8% 11% 41%	1800
	11th to 20th	Night	7% 4 2 6% 6% 4 5% 7% 7% 10% 43%	1824
	21st to end	Night	8% 4 2 4 3 3 4 5% 6% 9% 51%	1980
October	1st to 10th	Night	6% 3 1 4 4 2 4 4 4 7% 60%	2070
	11th to 20th	Night	6% 3 2 4 4 2 4 4 5% 8% 60%	2160
	21st to end	Night	11% 4 2 4 4 2 3 4 4 6% 56%	2376
November	1st to 10th	Night	9% 5% 2 4 4 3 4 3 4 6% 56%	2220
	11th to 20th	Night	11% 4 2 4 4 2 4 3 5% 6% 55%	2280
	21st to end	Night	10% 6% 2 5% 5% 3 4 4 5% 6% 49%	2450
December	1st to 10th	Night	13% 7% 2 5% 6% 3 4 4 4 7% 46%	2470
	11th to 20th	Night	12% 8% 3 5% 5% 3 4 5% 5% 7% 44%	2837
	21st to end	Night	16% 10% 3 6% 5% 3 4 4 4 5% 40%	4180

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	43% 5% 8% 16% 19% 10%	2848
	11th to 20th	Day	32% 5% 6% 18% 32% 7%	2886
	21st to end	Day	53% 5% 5% 12% 18% 6%	3476
February	1st to 10th	Day	45% 6% 9% 13% 17% 9%	1900
	11th to 20th	Day	40% 6% 9% 18% 18% 9%	1848
	21st to end	Day	47% 7% 10% 14% 17% 6%	1480
March	1st to 10th	Day	42% 7% 8% 20% 18% 5%	1914
	11th to 20th	Day	42% 7% 11% 15% 19% 6%	1980
	21st to end	Day	34% 6% 13% 22% 18% 6%	2268
April	1st to 10th	Day	35% 9% 15% 16% 17% 8%	2160
	11th to 20th	Day	40% 6% 10% 21% 16% 7%	2134
	21st to end	Day	32% 7% 11% 22% 22% 6%	2160
May	1st to 10th	Day	32% 7% 13% 23% 18% 7%	2160
	11th to 20th	Day	35% 8% 14% 23% 18% 2	2128
	21st to end	Day	35% 10% 15% 23% 15% 1	2337
June	1st to 10th	Day	45% 10% 16% 20% 8% 1	2160
	11th to 20th	Day	40% 12% 15% 22% 10% 1	2277
	21st to end	Day	49% 13% 17% 15% 6%	2340
July	1st to 10th	Day	53% 12% 18% 15% 2	2276
	11th to 20th	Day	51% 15% 19% 12% 3	2227
	21st to end	Day	47% 13% 20% 16% 4	2219
August	1st to 10th	Day	44% 13% 24% 16% 4	2136
	11th to 20th	Day	51% 14% 19% 13% 3 1	2125
	21st to end	Day	47% 12% 18% 14% 7% 2	2376
September	1st to 10th	Day	44% 12% 17% 13% 11% 4	2160
	11th to 20th	Day	44% 9% 15% 14% 14% 4	2116
	21st to end	Day	36% 8% 12% 20% 15% 8%	1980
October	1st to 10th	Day	29% 6% 12% 20% 21% 11%	1886
	11th to 20th	Day	29% 6% 10% 18% 23% 14%	1800
	21st to end	Day	31% 5% 8% 17% 26% 14%	1980
November	1st to 10th	Day	29% 5% 9% 23% 26% 8%	1858
	11th to 20th	Day	32% 5% 6% 20% 24% 12%	1900
	21st to end	Day	39% 7% 8% 18% 18% 10%	1723
December	1st to 10th	Day	40% 7% 10% 21% 16% 7%	1710
	11th to 20th	Day	44% 5% 8% 14% 21% 8%	2342
	21st to end	Day	46% 7% 9% 13% 22% 3	3472
January	1st to 10th	Night	41% 5% 7% 15% 22% 10%	4088
	11th to 20th	Night	33% 5% 6% 18% 27% 10%	4059
	21st to end	Night	47% 4 6% 14% 20% 9%	4180
February	1st to 10th	Night	42% 4 8% 17% 19% 10%	2280
	11th to 20th	Night	41% 5% 7% 16% 19% 12%	2214
	21st to end	Night	43% 6% 11% 14% 14% 11%	1776
March	1st to 10th	Night	37% 6% 10% 17% 21% 9%	2060
	11th to 20th	Night	38% 8% 15% 16% 16% 8%	1980
	21st to end	Night	31% 5% 13% 22% 22% 7%	2088
April	1st to 10th	Night	35% 7% 13% 19% 16% 11%	1800
	11th to 20th	Night	37% 6% 11% 21% 16% 9%	1775
	21st to end	Night	27% 5% 12% 24% 25% 7%	1800
May	1st to 10th	Night	26% 6% 12% 30% 19% 7%	1800
	11th to 20th	Night	31% 10% 15% 22% 20% 2	1770
	21st to end	Night	26% 9% 16% 30% 16% 2	1939
June	1st to 10th	Night	31% 10% 18% 28% 12%	1800
	11th to 20th	Night	26% 12% 21% 28% 13%	1674
	21st to end	Night	30% 12% 26% 23% 9%	1620
July	1st to 10th	Night	34% 12% 30% 21% 2	1575
	11th to 20th	Night	28% 19% 31% 18% 4	1606
	21st to end	Night	30% 13% 30% 23% 4	1858
August	1st to 10th	Night	20% 13% 34% 27% 6%	1778
	11th to 20th	Night	32% 16% 30% 19% 3	1776
	21st to end	Night	35% 12% 25% 19% 7% 3	1980
September	1st to 10th	Night	33% 12% 22% 17% 13% 4	1800
	11th to 20th	Night	33% 12% 16% 19% 14% 6%	1824
	21st to end	Night	29% 7% 15% 25% 15% 8%	1980
October	1st to 10th	Night	25% 5% 11% 23% 21% 14%	2070
	11th to 20th	Night	24% 5% 9% 21% 25% 14%	2160
	21st to end	Night	30% 4 7% 16% 29% 15%	2376
November	1st to 10th	Night	29% 6% 7% 22% 25% 11%	2220
	11th to 20th	Night	31% 4 8% 18% 27% 12%	2280
	21st to end	Night	36% 5% 7% 20% 22% 10%	2450
December	1st to 10th	Night	39% 5% 9% 22% 19% 7%	2470
	11th to 20th	Night	40% 6% 8% 15% 17% 14%	2838
	21st to end	Night	47% 5% 9% 16% 17% 7%	4180

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	16% 14% 33% 29% 7% 2	270
	11th to 20th	Day	13% 15% 29% 32% 10% 1	270
	21st to end	Day	21% 13% 38% 23% 5% 1	297
February	1st to 10th	Day	19% 11% 37% 24% 7% 1	270
	11th to 20th	Day	24% 9% 33% 22% 10% 2	267
	21st to end	Day	11% 15% 45% 22% 7% 1	198
March	1st to 10th	Day	13% 12% 38% 28% 9% 1	240
	11th to 20th	Day	18% 11% 35% 26% 8% 1	240
	21st to end	Day	14% 9% 31% 33% 12% 2	354
April	1st to 10th	Day	10% 8% 32% 34% 14% 2	420
	11th to 20th	Day	17% 11% 26% 25% 18% 3	412
	21st to end	Day	7% 7% 23% 35% 24% 4	420
May	1st to 10th	Day	8% 5% 20% 31% 28% 7%	423
	11th to 20th	Day	8% 3 17% 31% 30% 11%	447
	21st to end	Day	7% 1 6% 30% 36% 20%	485
June	1st to 10th	Day	10% 2 8% 23% 32% 26%	450
	11th to 20th	Day	7% 1 8% 24% 37% 23%	567
	21st to end	Day	8% 1 7% 23% 33% 27%	630
July	1st to 10th	Day	11% 2 3 15% 33% 34%	621
	11th to 20th	Day	7% 2 4 10% 37% 40%	574
	21st to end	Day	9% 3 12% 32% 43%	488
August	1st to 10th	Day	4 1 4 11% 34% 46%	446
	11th to 20th	Day	10% 1 2 8% 28% 51%	439
	21st to end	Day	9% 3 7% 12% 34% 36%	495
September	1st to 10th	Day	9% 2 4 15% 39% 32%	450
	11th to 20th	Day	11% 2 7% 19% 38% 23%	450
	21st to end	Day	9% 2 6% 25% 39% 20%	450
October	1st to 10th	Day	5% 1 13% 39% 31% 11%	356
	11th to 20th	Day	6% 4 13% 37% 27% 13%	270
	21st to end	Day	17% 7% 18% 29% 22% 7%	297
November	1st to 10th	Day	12% 3 16% 33% 30% 7%	270
	11th to 20th	Day	16% 7% 26% 28% 19% 4	270
	21st to end	Day	16% 9% 29% 30% 13% 4	270
December	1st to 10th	Day	16% 7% 30% 26% 15% 7%	270
	11th to 20th	Day	16% 11% 34% 31% 7%	270
	21st to end	Day	23% 7% 30% 23% 14% 2	297
January	1st to 10th	Night	18% 8% 30% 36% 8% 1	943
	11th to 20th	Night	17% 7% 27% 40% 10%	915
	21st to end	Night	20% 8% 34% 33% 7%	836
February	1st to 10th	Night	17% 7% 30% 37% 7% 1	760
	11th to 20th	Night	19% 8% 29% 32% 11%	742
	21st to end	Night	19% 9% 34% 32% 5%	592
March	1st to 10th	Night	13% 9% 32% 35% 11%	620
	11th to 20th	Night	15% 4 27% 37% 16% 1	540
	21st to end	Night	10% 8% 25% 38% 18%	594
April	1st to 10th	Night	14% 8% 25% 39% 15% 1	540
	11th to 20th	Night	14% 7% 28% 33% 17% 1	533
	21st to end	Night	6% 4 23% 43% 23% 1	540
May	1st to 10th	Night	8% 2 17% 44% 28% 1	540
	11th to 20th	Night	7% 2 12% 45% 31% 3	531
	21st to end	Night	7% 1 9% 32% 41% 10%	584
June	1st to 10th	Night	8% 2 3 32% 45% 10%	540
	11th to 20th	Night	4 1 4 23% 54% 14%	540
	21st to end	Night	8% 1 6% 20% 43% 22%	540
July	1st to 10th	Night	6% 2 3 10% 51% 29%	525
	11th to 20th	Night	4 1 1 5% 52% 36%	522
	21st to end	Night	5% 1 2 12% 50% 30%	591
August	1st to 10th	Night	2 1 10% 50% 38%	537
	11th to 20th	Night	5% 1 2 9% 45% 39%	534
	21st to end	Night	7% 1 5% 15% 44% 28%	594
September	1st to 10th	Night	8% 1 3 17% 48% 24%	540
	11th to 20th	Night	8% 1 4 22% 50% 15%	564
	21st to end	Night	9% 1 6% 28% 46% 9%	720
October	1st to 10th	Night	7% 1 10% 38% 38% 6%	720
	11th to 20th	Night	7% 3 15% 34% 34% 6%	720
	21st to end	Night	13% 4 19% 35% 27% 3	792
November	1st to 10th	Night	10% 4 13% 41% 29% 3	740
	11th to 20th	Night	14% 4 20% 39% 21% 2	760
	21st to end	Night	12% 5% 25% 38% 18% 1	760
December	1st to 10th	Night	15% 7% 24% 33% 20% 1	760
	11th to 20th	Night	16% 5% 25% 39% 14% 1	760
	21st to end	Night	21% 8% 26% 33% 11% 1	836

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