Lake Bob Sandlin State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Bob Sandlin State Park clear sky chart from 2005-11-06 to 2025-01-22.

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	12% 6% 2 5% 4 4 4 3 5% 7% 47%	105428
	Night	11% 6% 2 5% 3 3 3 3 5% 7% 52%	104034
Transparency	Day	36% 4 10% 24% 21% 6%	109092
	Night	32% 3 9% 22% 24% 10%	108483
Seeing	Day	13% 6% 19% 27% 24% 10%	15419
	Night	14% 6% 23% 34% 20% 2	25369

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	16% 9% 3 5% 3 3 2 2 4 5% 47%	2937
	11th to 20th	Day	15% 5% 2 4 2 2 3 3 5% 5% 56%	2940
	21st to end	Day	23% 10% 2 6% 3 2 2 2 3 4 44%	3144
February	1st to 10th	Day	20% 9% 2 8% 4 4 3 2 4 4 41%	1710
	11th to 20th	Day	19% 8% 3 5% 5% 3 3 3 4 4 42%	1815
	21st to end	Day	20% 8% 3 5% 3 2 3 2 3 4 46%	1708
March	1st to 10th	Day	14% 11% 3 6% 4 4 3 3 4 6% 42%	3436
	11th to 20th	Day	18% 6% 2 6% 5% 4 4 3 6% 7% 38%	3480
	21st to end	Day	15% 9% 3 7% 5% 4 4 3 5% 7% 38%	3814
April	1st to 10th	Day	12% 7% 2 7% 5% 4 4 3 5% 6% 46%	2109
	11th to 20th	Day	15% 7% 2 5% 3 4 4 4 6% 7% 43%	2254
	21st to end	Day	12% 5% 2 6% 5% 4 5% 4 8% 6% 44%	2280
May	1st to 10th	Day	17% 9% 3 7% 5% 4 4 3 5% 6% 36%	4018
	11th to 20th	Day	13% 7% 2 6% 4 3 4 4 5% 6% 46%	4082
	21st to end	Day	15% 7% 3 7% 5% 5% 5% 4 6% 8% 35%	4477
June	1st to 10th	Day	5% 5% 1 6% 4 4 5% 5% 7% 10% 46%	2470
	11th to 20th	Day	4 4 2 5% 4 6% 6% 5% 7% 10% 47%	2470
	21st to end	Day	5% 3 1 4 4 4 6% 5% 7% 10% 51%	2470
July	1st to 10th	Day	8% 6% 2 6% 5% 5% 5% 5% 7% 9% 43%	4120
	11th to 20th	Day	3 3 1 4 3 4 4 3 6% 11% 57%	4120
	21st to end	Day	8% 8% 3 8% 6% 5% 5% 5% 7% 8% 36%	4465
August	1st to 10th	Day	2 1 1 2 3 3 4 3 6% 8% 68%	4104
	11th to 20th	Day	5% 3 1 3 4 4 4 5% 7% 10% 55%	3961
	21st to end	Day	4 4 2 6% 5% 6% 6% 5% 8% 12% 43%	4180
September	1st to 10th	Day	9% 5% 2 6% 4 4 4 3 6% 6% 50%	2166
	11th to 20th	Day	10% 5% 2 7% 4 5% 4 3 6% 8% 45%	2090
	21st to end	Day	7% 4 1 4 3 3 4 3 5% 7% 58%	2090
October	1st to 10th	Day	6% 3 2 3 3 4 4 3 5% 7% 60%	1936
	11th to 20th	Day	13% 4 1 4 3 3 3 3 4 6% 57%	1900
	21st to end	Day	14% 5% 2 5% 3 2 2 2 3 4 57%	2090
November	1st to 10th	Day	12% 6% 2 5% 3 3 3 4 4 6% 51%	1958
	11th to 20th	Day	10% 4 2 5% 4 3 3 3 4 6% 56%	2000
	21st to end	Day	17% 7% 2 5% 4 3 3 2 3 5% 51%	1815
December	1st to 10th	Day	18% 5% 2 5% 3 3 2 2 4 6% 50%	2940
	11th to 20th	Day	15% 10% 3 7% 4 4 4 3 5% 5% 42%	3391
	21st to end	Day	17% 10% 4 6% 3 3 3 3 3 5% 44%	4488
January	1st to 10th	Night	14% 9% 3 6% 3 3 3 3 3 5% 49%	4238
	11th to 20th	Night	15% 6% 2 4 3 2 2 2 4 4 57%	4250
	21st to end	Night	24% 8% 2 5% 2 2 2 2 3 4 45%	4546
February	1st to 10th	Night	16% 7% 3 5% 4 3 3 2 4 5% 48%	2470
	11th to 20th	Night	18% 7% 3 6% 4 3 3 2 3 4 46%	2269
	21st to end	Night	18% 7% 2 4 4 2 3 3 3 5% 50%	1744
March	1st to 10th	Night	19% 9% 3 6% 4 4 4 2 5% 6% 39%	3419
	11th to 20th	Night	15% 7% 3 6% 4 4 4 3 5% 7% 43%	3480
	21st to end	Night	13% 6% 3 6% 4 4 3 4 5% 6% 45%	3817
April	1st to 10th	Night	10% 6% 2 5% 4 4 3 4 6% 7% 51%	2069
	11th to 20th	Night	11% 6% 2 5% 4 3 3 5% 5% 7% 48%	1875
	21st to end	Night	11% 6% 1 5% 4 3 4 3 5% 7% 52%	1900
May	1st to 10th	Night	13% 8% 3 8% 5% 4 4 3 6% 7% 39%	2869
	11th to 20th	Night	11% 7% 2 6% 4 3 3 3 5% 8% 47%	2823
	21st to end	Night	12% 7% 2 6% 4 5% 4 3 6% 9% 42%	3090
June	1st to 10th	Night	3 5% 2 4 3 4 4 4 6% 10% 56%	1710
	11th to 20th	Night	4 4 2 4 3 2 3 3 6% 8% 63%	1710
	21st to end	Night	4 3 1 2 4 4 4 4 7% 10% 58%	1710
July	1st to 10th	Night	6% 4 1 4 3 3 4 4 7% 11% 52%	2850
	11th to 20th	Night	3 3 1 2 2 2 3 3 6% 12% 63%	2850
	21st to end	Night	5% 6% 2 6% 5% 5% 5% 4 7% 8% 45%	3098
August	1st to 10th	Night	2 1 1 1 2 2 2 5% 8% 74%	2836
	11th to 20th	Night	3 3 1 3 3 3 3 3 6% 10% 63%	2860
	21st to end	Night	3 2 1 4 4 4 5% 5% 7% 10% 56%	3476
September	1st to 10th	Night	7% 5% 1 4 4 4 4 3 6% 8% 56%	2008
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 5% 7% 54%	2090
	21st to end	Night	6% 3 1 4 3 3 3 3 4 7% 63%	2090
October	1st to 10th	Night	5% 3 1 4 3 3 3 3 4 6% 66%	2223
	11th to 20th	Night	11% 4 1 3 3 2 3 2 4 6% 62%	2280
	21st to end	Night	15% 4 2 4 3 2 2 2 3 4 60%	2508
November	1st to 10th	Night	12% 5% 2 4 3 3 3 2 4 6% 57%	2340
	11th to 20th	Night	8% 5% 2 5% 4 3 3 3 4 6% 58%	2400
	21st to end	Night	15% 6% 2 5% 3 3 3 2 3 6% 52%	2580
December	1st to 10th	Night	16% 7% 2 4 3 3 3 2 4 5% 52%	4250
	11th to 20th	Night	14% 7% 3 7% 4 4 3 2 4 4 47%	4816
	21st to end	Night	14% 10% 3 6% 3 3 3 2 3 4 49%	6490

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	42% 2 5% 21% 25% 4	2938
	11th to 20th	Day	32% 2 8% 25% 28% 4	2940
	21st to end	Day	47% 1 3 16% 23% 8%	3144
February	1st to 10th	Day	49% 3 5% 17% 19% 7%	1710
	11th to 20th	Day	47% 3 5% 19% 19% 8%	1825
	21st to end	Day	44% 2 5% 15% 24% 9%	1708
March	1st to 10th	Day	44% 4 6% 15% 24% 7%	3436
	11th to 20th	Day	46% 3 8% 24% 16% 4	3480
	21st to end	Day	46% 3 9% 19% 20% 3	3814
April	1st to 10th	Day	40% 3 8% 22% 18% 8%	2109
	11th to 20th	Day	40% 4 10% 19% 19% 8%	2254
	21st to end	Day	39% 5% 9% 22% 21% 4	2280
May	1st to 10th	Day	49% 3 9% 25% 11% 3	4055
	11th to 20th	Day	39% 3 10% 26% 21% 1	4086
	21st to end	Day	47% 5% 13% 20% 11% 3	4489
June	1st to 10th	Day	31% 6% 16% 28% 17% 2	2470
	11th to 20th	Day	31% 5% 15% 26% 19% 3	2470
	21st to end	Day	26% 7% 12% 31% 20% 3	2470
July	1st to 10th	Day	35% 7% 22% 26% 9%	4056
	11th to 20th	Day	21% 5% 13% 40% 20% 1	4051
	21st to end	Day	43% 6% 14% 28% 9%	4325
August	1st to 10th	Day	16% 4 12% 33% 29% 6%	4090
	11th to 20th	Day	24% 5% 18% 39% 13% 1	4000
	21st to end	Day	31% 8% 17% 29% 13% 2	4179
September	1st to 10th	Day	34% 5% 10% 22% 19% 10%	2166
	11th to 20th	Day	37% 5% 11% 20% 20% 7%	2090
	21st to end	Day	27% 4 9% 22% 27% 11%	2090
October	1st to 10th	Day	15% 2 7% 12% 27% 37%	3209
	11th to 20th	Day	20% 2 3 19% 33% 23%	3140
	21st to end	Day	26% 3 4 26% 33% 8%	3428
November	1st to 10th	Day	35% 3 8% 21% 25% 9%	1958
	11th to 20th	Day	31% 2 8% 19% 28% 11%	2000
	21st to end	Day	39% 2 5% 18% 27% 9%	1815
December	1st to 10th	Day	39% 2 5% 27% 23% 5%	2940
	11th to 20th	Day	45% 3 4 16% 25% 7%	3389
	21st to end	Day	45% 2 4 20% 24% 5%	4488
January	1st to 10th	Night	40% 3 4 16% 31% 7%	4238
	11th to 20th	Night	33% 2 7% 19% 28% 10%	4250
	21st to end	Night	46% 2 6% 15% 23% 9%	4546
February	1st to 10th	Night	40% 3 6% 20% 20% 11%	2470
	11th to 20th	Night	44% 2 5% 16% 23% 9%	2269
	21st to end	Night	40% 2 7% 16% 21% 14%	1744
March	1st to 10th	Night	48% 3 6% 14% 18% 11%	3419
	11th to 20th	Night	43% 3 8% 19% 19% 8%	3480
	21st to end	Night	40% 3 9% 19% 24% 4	3817
April	1st to 10th	Night	33% 3 11% 21% 19% 13%	2069
	11th to 20th	Night	35% 4 8% 20% 21% 11%	1875
	21st to end	Night	33% 3 10% 23% 26% 5%	1900
May	1st to 10th	Night	45% 5% 9% 22% 13% 5%	2896
	11th to 20th	Night	36% 3 14% 22% 22% 2	2824
	21st to end	Night	38% 4 15% 25% 13% 5%	3099
June	1st to 10th	Night	23% 5% 16% 29% 23% 4	1710
	11th to 20th	Night	20% 5% 14% 34% 22% 5%	1710
	21st to end	Night	20% 5% 13% 32% 26% 3	1710
July	1st to 10th	Night	25% 5% 22% 35% 12%	2805
	11th to 20th	Night	16% 4 13% 43% 21% 3	2796
	21st to end	Night	34% 7% 16% 31% 12% 1	2999
August	1st to 10th	Night	10% 3 13% 31% 36% 7%	2826
	11th to 20th	Night	18% 3 16% 42% 18% 4	2887
	21st to end	Night	22% 7% 16% 29% 24% 2	3476
September	1st to 10th	Night	27% 5% 12% 24% 23% 10%	2008
	11th to 20th	Night	31% 4 9% 25% 21% 10%	2090
	21st to end	Night	22% 3 9% 21% 30% 15%	2090
October	1st to 10th	Night	13% 2 5% 15% 22% 44%	3704
	11th to 20th	Night	17% 2 4 15% 35% 27%	3779
	21st to end	Night	25% 2 4 23% 29% 17%	4120
November	1st to 10th	Night	31% 3 8% 17% 28% 13%	2340
	11th to 20th	Night	29% 3 5% 21% 27% 16%	2400
	21st to end	Night	37% 2 6% 18% 26% 10%	2580
December	1st to 10th	Night	38% 2 6% 21% 26% 7%	4250
	11th to 20th	Night	43% 2 6% 15% 23% 11%	4817
	21st to end	Night	41% 3 5% 19% 27% 7%	6490

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	24% 10% 35% 21% 9%	300
	11th to 20th	Day	19% 15% 38% 20% 8%	300
	21st to end	Day	21% 15% 38% 19% 7%	300
February	1st to 10th	Day	26% 9% 40% 19% 6% 1	270
	11th to 20th	Day	29% 11% 39% 17% 4	270
	21st to end	Day	31% 17% 38% 10% 4	225
March	1st to 10th	Day	20% 13% 36% 23% 8%	270
	11th to 20th	Day	23% 14% 37% 20% 5% 1	270
	21st to end	Day	18% 15% 37% 23% 7% 1	297
April	1st to 10th	Day	20% 13% 35% 24% 7% 1	289
	11th to 20th	Day	23% 10% 29% 25% 11% 1	452
	21st to end	Day	18% 9% 28% 28% 13% 3	460
May	1st to 10th	Day	14% 8% 31% 34% 13% 1	614
	11th to 20th	Day	13% 4 24% 35% 19% 5%	675
	21st to end	Day	15% 3 18% 37% 21% 7%	734
June	1st to 10th	Day	8% 4 10% 30% 37% 13%	680
	11th to 20th	Day	5% 2 11% 38% 33% 11%	680
	21st to end	Day	4 2 9% 29% 38% 17%	680
July	1st to 10th	Day	7% 2 6% 28% 39% 18%	671
	11th to 20th	Day	3 1 4 27% 44% 21%	668
	21st to end	Day	5% 2 3 26% 43% 21%	739
August	1st to 10th	Day	4 1 4 23% 46% 22%	676
	11th to 20th	Day	10% 1 2 25% 43% 18%	624
	21st to end	Day	9% 3 3 18% 39% 29%	539
September	1st to 10th	Day	10% 1 6% 19% 39% 26%	376
	11th to 20th	Day	4 2 9% 22% 33% 29%	300
	21st to end	Day	11% 3 8% 27% 31% 21%	300
October	1st to 10th	Day	3 2 12% 41% 29% 13%	300
	11th to 20th	Day	12% 5% 28% 29% 19% 8%	300
	21st to end	Day	23% 7% 21% 30% 15% 5%	330
November	1st to 10th	Day	17% 6% 30% 27% 18% 3	300
	11th to 20th	Day	14% 9% 27% 36% 13% 2	300
	21st to end	Day	20% 12% 29% 25% 13% 1	300
December	1st to 10th	Day	20% 12% 30% 24% 11% 2	300
	11th to 20th	Day	19% 10% 39% 23% 8% 1	300
	21st to end	Day	23% 12% 38% 20% 6% 1	330
January	1st to 10th	Night	19% 11% 30% 33% 7%	1000
	11th to 20th	Night	20% 12% 33% 28% 7% 1	1000
	21st to end	Night	20% 8% 37% 29% 5%	1051
February	1st to 10th	Night	21% 9% 35% 28% 7%	950
	11th to 20th	Night	25% 10% 36% 27% 3	794
	21st to end	Night	23% 14% 38% 22% 3	488
March	1st to 10th	Night	21% 9% 32% 30% 8%	570
	11th to 20th	Night	19% 7% 33% 35% 6%	570
	21st to end	Night	15% 8% 34% 36% 7%	627
April	1st to 10th	Night	13% 7% 42% 31% 8%	570
	11th to 20th	Night	14% 9% 35% 30% 11% 1	563
	21st to end	Night	14% 7% 34% 32% 11% 1	570
May	1st to 10th	Night	11% 5% 33% 40% 11% 1	570
	11th to 20th	Night	11% 4 24% 39% 19% 2	561
	21st to end	Night	9% 3 20% 43% 22% 3	617
June	1st to 10th	Night	5% 2 10% 38% 43% 3	570
	11th to 20th	Night	5% 1 12% 45% 35% 3	570
	21st to end	Night	5% 1 8% 32% 45% 8%	570
July	1st to 10th	Night	4 2 3 38% 49% 4	555
	11th to 20th	Night	3 4 35% 51% 7%	552
	21st to end	Night	3 1 4 34% 50% 8%	624
August	1st to 10th	Night	3 1 2 33% 53% 7%	567
	11th to 20th	Night	8% 1 3 31% 50% 7%	564
	21st to end	Night	5% 1 3 31% 51% 9%	627
September	1st to 10th	Night	11% 1 5% 32% 43% 8%	570
	11th to 20th	Night	12% 2 6% 31% 45% 4	570
	21st to end	Night	8% 1 10% 38% 39% 5%	570
October	1st to 10th	Night	6% 2 11% 44% 33% 3	703
	11th to 20th	Night	13% 4 23% 39% 20% 2	760
	21st to end	Night	18% 5% 24% 33% 18% 2	836
November	1st to 10th	Night	13% 4 22% 43% 16% 2	780
	11th to 20th	Night	11% 7% 29% 41% 12% 1	800
	21st to end	Night	18% 10% 28% 31% 13%	980
December	1st to 10th	Night	17% 10% 29% 38% 6%	1000
	11th to 20th	Night	20% 9% 28% 36% 7%	1000
	21st to end	Night	20% 10% 30% 32% 7%	1100

Page generated at 2025-01-19 02:06:46. Version ac07

Copyright © 2025 Attilla Danko.