Lake Taayer
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Taayer clear sky chart from 2005-11-06 to 2026-09-29.

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	10% 7% 3 7% 5% 4 5% 4 6% 8% 41%	158372
	Night	9% 8% 3 8% 5% 5% 5% 4 6% 7% 41%	150497
Transparency	Day	41% 5% 14% 27% 12% 1	153028
	Night	42% 5% 14% 25% 13% 1	146851
Seeing	Day	15% 9% 30% 30% 14% 3	18760
	Night	14% 7% 33% 35% 10% 1	28550

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	6% 10% 4 15% 12% 10% 10% 6% 6% 6% 14%	4279
	11th to 20th	Day	4 8% 4 12% 8% 9% 12% 8% 8% 9% 19%	4740
	21st to end	Day	3 8% 6% 15% 8% 6% 6% 4 6% 9% 30%	5245
February	1st to 10th	Day	9% 12% 5% 11% 7% 7% 6% 5% 6% 6% 27%	1890
	11th to 20th	Day	7% 10% 4 11% 7% 7% 7% 6% 6% 7% 29%	1876
	21st to end	Day	8% 11% 5% 13% 7% 6% 5% 3 6% 9% 27%	1730
March	1st to 10th	Day	9% 9% 3 8% 5% 4 4 4 4 6% 43%	4690
	11th to 20th	Day	9% 10% 3 8% 5% 5% 5% 4 6% 9% 37%	5090
	21st to end	Day	18% 13% 5% 12% 6% 4 4 3 5% 7% 23%	5585
April	1st to 10th	Day	15% 9% 3 7% 5% 3 4 4 6% 7% 39%	2478
	11th to 20th	Day	17% 11% 4 7% 5% 4 4 3 5% 7% 34%	2699
	21st to end	Day	20% 10% 3 7% 5% 3 4 4 5% 5% 34%	2730
May	1st to 10th	Day	9% 5% 2 5% 4 4 4 3 5% 6% 53%	7655
	11th to 20th	Day	18% 8% 2 5% 3 3 4 3 5% 6% 44%	7802
	21st to end	Day	15% 7% 2 6% 4 4 4 4 6% 8% 40%	9643
June	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 7% 9% 42%	3150
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 7% 8% 42%	3150
	21st to end	Day	10% 4 1 6% 4 4 5% 5% 7% 8% 45%	3150
July	1st to 10th	Day	8% 4 2 6% 4 4 5% 4 7% 11% 45%	8849
	11th to 20th	Day	6% 4 1 4 3 3 3 3 5% 8% 60%	8551
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 7% 10% 45%	8927
August	1st to 10th	Day	10% 4 2 5% 4 4 4 4 6% 8% 50%	7581
	11th to 20th	Day	12% 6% 2 7% 4 5% 5% 4 7% 9% 40%	7598
	21st to end	Day	7% 4 2 4 3 4 4 4 6% 8% 56%	8408
September	1st to 10th	Day	10% 3 1 5% 3 4 4 4 6% 7% 53%	2494
	11th to 20th	Day	12% 5% 2 5% 5% 4 5% 3 5% 8% 46%	2310
	21st to end	Day	14% 6% 2 6% 2 4 3 3 5% 6% 50%	2288
October	1st to 10th	Day	12% 4 1 3 3 3 3 3 5% 7% 56%	3407
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 4 6% 51%	3240
	21st to end	Day	13% 9% 2 6% 4 3 4 3 5% 8% 43%	3190
November	1st to 10th	Day	12% 11% 3 8% 4 4 4 3 6% 7% 38%	1853
	11th to 20th	Day	9% 11% 4 10% 6% 5% 5% 3 5% 7% 36%	1694
	21st to end	Day	9% 9% 4 10% 7% 5% 4 4 6% 6% 36%	1680
December	1st to 10th	Day	7% 11% 5% 12% 10% 7% 8% 4 6% 7% 23%	2432
	11th to 20th	Day	8% 14% 7% 13% 6% 7% 6% 4 5% 7% 24%	2713
	21st to end	Day	15% 13% 3 14% 6% 4 4 4 4 5% 27%	3575
January	1st to 10th	Night	5% 9% 4 14% 11% 10% 9% 6% 7% 8% 17%	8641
	11th to 20th	Night	4 9% 4 10% 7% 8% 11% 6% 8% 8% 24%	8250
	21st to end	Night	4 8% 6% 11% 6% 6% 6% 6% 8% 8% 33%	8956
February	1st to 10th	Night	8% 12% 4 10% 6% 6% 5% 4 6% 7% 31%	2730
	11th to 20th	Night	7% 10% 3 10% 6% 4 5% 5% 7% 6% 37%	2650
	21st to end	Night	9% 10% 3 8% 6% 6% 6% 5% 5% 7% 36%	2076
March	1st to 10th	Night	7% 7% 3 7% 5% 4 4 4 7% 8% 44%	5400
	11th to 20th	Night	10% 9% 3 8% 5% 5% 5% 4 6% 7% 37%	5090
	21st to end	Night	17% 13% 4 9% 5% 4 4 4 5% 7% 29%	5588
April	1st to 10th	Night	12% 9% 3 7% 5% 4 5% 3 5% 6% 41%	2137
	11th to 20th	Night	16% 9% 3 7% 4 3 3 3 5% 7% 40%	1869
	21st to end	Night	18% 8% 3 8% 4 4 4 3 5% 6% 37%	1890
May	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 5% 7% 52%	5292
	11th to 20th	Night	13% 7% 2 5% 3 3 3 3 5% 6% 48%	5086
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 8% 45%	4550
June	1st to 10th	Night	9% 5% 2 4 3 3 4 3 6% 9% 49%	1470
	11th to 20th	Night	9% 5% 2 5% 3 4 5% 3 7% 9% 48%	1470
	21st to end	Night	7% 4 1 5% 3 3 3 3 6% 8% 57%	1470
July	1st to 10th	Night	8% 4 2 5% 3 4 5% 4 6% 9% 50%	4140
	11th to 20th	Night	5% 2 1 4 2 3 3 3 5% 9% 63%	4435
	21st to end	Night	7% 5% 2 6% 4 5% 5% 4 7% 9% 48%	5168
August	1st to 10th	Night	8% 4 2 5% 4 4 4 3 6% 7% 53%	5241
	11th to 20th	Night	11% 5% 2 6% 4 5% 5% 4 6% 8% 45%	5258
	21st to end	Night	7% 3 2 5% 3 3 4 3 5% 8% 57%	5808
September	1st to 10th	Night	7% 4 1 5% 3 4 4 3 4 7% 60%	2124
	11th to 20th	Night	10% 6% 2 4 3 3 3 3 5% 6% 55%	2310
	21st to end	Night	13% 4 2 4 2 3 3 3 4 6% 56%	2288
October	1st to 10th	Night	8% 4 2 4 2 3 3 3 4 5% 62%	3740
	11th to 20th	Night	13% 5% 2 6% 3 3 4 4 5% 7% 48%	3899
	21st to end	Night	13% 7% 2 7% 4 4 3 3 4 7% 45%	4609
November	1st to 10th	Night	9% 10% 3 7% 4 4 5% 3 6% 7% 41%	2665
	11th to 20th	Night	8% 11% 4 10% 6% 5% 4 3 5% 6% 39%	2924
	21st to end	Night	10% 8% 3 9% 5% 4 4 3 5% 7% 40%	2940
December	1st to 10th	Night	5% 10% 4 12% 8% 7% 5% 4 6% 7% 32%	4974
	11th to 20th	Night	7% 12% 5% 12% 8% 6% 6% 4 5% 6% 27%	5714
	21st to end	Night	14% 13% 5% 13% 7% 5% 4 4 5% 5% 26%	7645

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	68% 5% 11% 10% 5% 1	4281
	11th to 20th	Day	58% 5% 16% 15% 6%	4740
	21st to end	Day	51% 5% 15% 20% 9%	5245
February	1st to 10th	Day	56% 6% 12% 17% 8% 1	1890
	11th to 20th	Day	52% 5% 14% 21% 7% 1	1885
	21st to end	Day	54% 4 15% 19% 7%	1730
March	1st to 10th	Day	41% 5% 14% 31% 8% 1	4690
	11th to 20th	Day	43% 5% 14% 28% 9% 1	5090
	21st to end	Day	61% 5% 14% 15% 4 1	5585
April	1st to 10th	Day	44% 5% 14% 25% 11% 1	2478
	11th to 20th	Day	50% 5% 12% 20% 13% 1	2702
	21st to end	Day	50% 5% 12% 24% 8% 1	2730
May	1st to 10th	Day	31% 5% 11% 34% 19% 1	7655
	11th to 20th	Day	41% 5% 7% 24% 19% 4	7806
	21st to end	Day	40% 5% 12% 30% 11% 1	9644
June	1st to 10th	Day	37% 6% 17% 28% 11% 1	3150
	11th to 20th	Day	38% 6% 16% 27% 12% 1	3150
	21st to end	Day	34% 7% 17% 29% 11% 1	3150
July	1st to 10th	Day	31% 7% 22% 29% 10% 1	8776
	11th to 20th	Day	23% 4 11% 36% 23% 3	8470
	21st to end	Day	32% 7% 17% 32% 11% 1	8729
August	1st to 10th	Day	28% 5% 15% 34% 16% 2	6000
	11th to 20th	Day	38% 8% 20% 28% 5% 1	5987
	21st to end	Day	28% 7% 17% 32% 15% 1	6592
September	1st to 10th	Day	29% 5% 14% 36% 14% 1	2494
	11th to 20th	Day	36% 6% 17% 29% 11% 1	2310
	21st to end	Day	36% 4 13% 31% 16% 1	2288
October	1st to 10th	Day	30% 3 10% 32% 23% 3	3407
	11th to 20th	Day	35% 4 10% 32% 18% 2	3240
	21st to end	Day	41% 4 16% 24% 15% 1	3190
November	1st to 10th	Day	45% 4 14% 24% 11% 2	1853
	11th to 20th	Day	48% 5% 16% 21% 9% 1	1694
	21st to end	Day	47% 5% 17% 23% 6% 2	1680
December	1st to 10th	Day	59% 6% 14% 16% 4	2432
	11th to 20th	Day	60% 6% 15% 17% 3	2710
	21st to end	Day	60% 3 12% 19% 6%	3575
January	1st to 10th	Night	61% 7% 13% 14% 5%	8642
	11th to 20th	Night	53% 6% 15% 17% 9%	8250
	21st to end	Night	47% 5% 17% 21% 10%	8956
February	1st to 10th	Night	51% 5% 15% 18% 10% 1	2730
	11th to 20th	Night	45% 5% 13% 24% 12% 1	2651
	21st to end	Night	47% 5% 14% 21% 12% 1	2076
March	1st to 10th	Night	36% 5% 16% 30% 11% 2	5400
	11th to 20th	Night	43% 7% 14% 25% 11% 1	5090
	21st to end	Night	54% 5% 14% 20% 7%	5588
April	1st to 10th	Night	43% 4 12% 26% 13% 1	2137
	11th to 20th	Night	44% 4 10% 25% 16% 2	1869
	21st to end	Night	47% 5% 11% 24% 11% 1	1890
May	1st to 10th	Night	30% 5% 10% 32% 20% 2	5293
	11th to 20th	Night	36% 5% 8% 25% 21% 6%	5087
	21st to end	Night	37% 6% 12% 30% 14% 1	4550
June	1st to 10th	Night	31% 4 18% 31% 13% 3	1470
	11th to 20th	Night	30% 6% 18% 27% 15% 4	1470
	21st to end	Night	25% 6% 20% 31% 15% 3	1470
July	1st to 10th	Night	29% 8% 16% 33% 12% 1	4105
	11th to 20th	Night	19% 6% 13% 38% 22% 2	4393
	21st to end	Night	31% 7% 20% 31% 10% 2	5054
August	1st to 10th	Night	26% 5% 14% 33% 21% 2	4146
	11th to 20th	Night	35% 8% 21% 26% 9% 1	4145
	21st to end	Night	29% 6% 15% 31% 18% 1	4555
September	1st to 10th	Night	26% 5% 14% 35% 20% 1	2124
	11th to 20th	Night	31% 4 16% 32% 16% 1	2310
	21st to end	Night	30% 4 11% 32% 20% 3	2288
October	1st to 10th	Night	25% 3 8% 30% 30% 4	3740
	11th to 20th	Night	35% 4 10% 30% 19% 2	3899
	21st to end	Night	40% 4 12% 28% 15% 1	4609
November	1st to 10th	Night	41% 5% 12% 23% 16% 3	2665
	11th to 20th	Night	46% 5% 14% 22% 12% 2	2924
	21st to end	Night	43% 5% 19% 24% 8% 1	2940
December	1st to 10th	Night	50% 5% 21% 17% 7%	4974
	11th to 20th	Night	56% 6% 15% 18% 5%	5716
	21st to end	Night	60% 5% 12% 16% 6%	7645

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	11% 9% 30% 39% 9% 2	330
	11th to 20th	Day	13% 13% 35% 31% 7% 1	330
	21st to end	Day	16% 11% 32% 32% 7% 1	363
February	1st to 10th	Day	14% 12% 39% 29% 5% 1	330
	11th to 20th	Day	12% 9% 39% 28% 10% 2	330
	21st to end	Day	14% 8% 41% 31% 5%	273
March	1st to 10th	Day	18% 10% 40% 25% 7% 1	330
	11th to 20th	Day	15% 12% 33% 25% 12% 3	330
	21st to end	Day	18% 9% 33% 26% 12% 3	363
April	1st to 10th	Day	21% 13% 34% 24% 6% 1	498
	11th to 20th	Day	25% 14% 29% 22% 9% 1	740
	21st to end	Day	24% 10% 29% 25% 11% 1	750
May	1st to 10th	Day	17% 8% 31% 31% 13% 1	753
	11th to 20th	Day	21% 9% 26% 29% 13% 2	775
	21st to end	Day	18% 8% 24% 29% 18% 4	844
June	1st to 10th	Day	11% 8% 27% 28% 19% 6%	780
	11th to 20th	Day	12% 11% 37% 26% 13% 2	780
	21st to end	Day	13% 7% 29% 34% 14% 3	780
July	1st to 10th	Day	8% 2 24% 36% 24% 6%	771
	11th to 20th	Day	7% 5% 29% 35% 19% 4	768
	21st to end	Day	6% 4 24% 39% 22% 5%	849
August	1st to 10th	Day	10% 5% 22% 37% 22% 4	776
	11th to 20th	Day	12% 3 26% 35% 18% 6%	765
	21st to end	Day	9% 6% 25% 34% 23% 3	858
September	1st to 10th	Day	12% 7% 28% 33% 17% 3	544
	11th to 20th	Day	16% 6% 33% 31% 13% 1	360
	21st to end	Day	18% 11% 25% 27% 14% 5%	354
October	1st to 10th	Day	17% 5% 30% 29% 15% 3	330
	11th to 20th	Day	17% 19% 27% 29% 8%	330
	21st to end	Day	20% 17% 35% 20% 7% 2	363
November	1st to 10th	Day	20% 10% 33% 30% 7% 1	330
	11th to 20th	Day	14% 11% 39% 27% 8% 1	330
	21st to end	Day	15% 14% 39% 23% 7% 1	330
December	1st to 10th	Day	15% 8% 38% 28% 10% 1	330
	11th to 20th	Day	17% 11% 42% 27% 3	330
	21st to end	Day	20% 10% 36% 25% 7% 2	363
January	1st to 10th	Night	11% 8% 40% 32% 8% 1	1050
	11th to 20th	Night	13% 9% 38% 32% 7%	1050
	21st to end	Night	13% 8% 38% 33% 7% 1	1155
February	1st to 10th	Night	13% 10% 35% 33% 8% 1	1050
	11th to 20th	Night	12% 7% 40% 31% 9% 2	1016
	21st to end	Night	13% 9% 33% 31% 12% 2	692
March	1st to 10th	Night	14% 7% 37% 31% 9% 1	798
	11th to 20th	Night	17% 7% 36% 31% 8%	630
	21st to end	Night	17% 8% 34% 29% 11% 1	693
April	1st to 10th	Night	16% 10% 37% 29% 7%	630
	11th to 20th	Night	21% 11% 28% 32% 8%	623
	21st to end	Night	22% 6% 29% 34% 9%	630
May	1st to 10th	Night	16% 6% 33% 36% 10% 1	630
	11th to 20th	Night	14% 5% 32% 38% 12%	621
	21st to end	Night	15% 6% 29% 37% 13% 1	683
June	1st to 10th	Night	11% 6% 27% 41% 14% 1	630
	11th to 20th	Night	11% 5% 35% 41% 8%	630
	21st to end	Night	8% 5% 28% 44% 15% 1	630
July	1st to 10th	Night	6% 3 23% 45% 22% 2	615
	11th to 20th	Night	4 2 26% 52% 15%	612
	21st to end	Night	6% 3 22% 50% 18% 1	690
August	1st to 10th	Night	7% 3 20% 54% 15% 1	627
	11th to 20th	Night	9% 3 23% 43% 19% 2	624
	21st to end	Night	6% 3 27% 45% 18% 1	693
September	1st to 10th	Night	8% 4 27% 41% 17% 2	630
	11th to 20th	Night	12% 4 26% 44% 13%	630
	21st to end	Night	15% 5% 31% 33% 15% 1	624
October	1st to 10th	Night	16% 9% 33% 33% 10%	685
	11th to 20th	Night	19% 9% 35% 29% 8%	800
	21st to end	Night	18% 10% 34% 31% 7%	1099
November	1st to 10th	Night	14% 11% 32% 34% 9%	1025
	11th to 20th	Night	13% 9% 38% 29% 9% 1	1050
	21st to end	Night	15% 9% 37% 33% 6%	1050
December	1st to 10th	Night	14% 8% 36% 33% 9%	1050
	11th to 20th	Night	17% 11% 34% 32% 6%	1050
	21st to end	Night	21% 8% 36% 28% 6% 1	1155

Page generated at 2026-09-26 03:18:44. Version ac07

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