Shreveport Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shreveport Observatory clear sky chart from 2005-11-06 to 2025-07-21.

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	13% 6% 2 6% 4 4 4 4 5% 7% 45%	120170
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 48%	119144
Transparency	Day	38% 6% 10% 20% 19% 7%	123818
	Night	35% 5% 10% 20% 21% 9%	123639
Seeing	Day	13% 6% 18% 25% 26% 12%	16071
	Night	14% 4 21% 35% 22% 3	25850

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	18% 10% 3 5% 3 3 3 2 4 5% 45%	4077
	11th to 20th	Day	15% 6% 1 4 3 3 3 3 4 7% 53%	4080
	21st to end	Day	23% 10% 2 5% 3 3 2 2 3 3 44%	4488
February	1st to 10th	Day	21% 10% 3 6% 4 4 2 3 4 4 39%	1800
	11th to 20th	Day	22% 9% 2 5% 4 3 5% 3 4 5% 39%	1912
	21st to end	Day	22% 8% 2 6% 5% 3 3 3 4 4 39%	1815
March	1st to 10th	Day	19% 10% 3 9% 4 3 3 2 3 5% 38%	4936
	11th to 20th	Day	15% 5% 2 5% 3 3 3 3 5% 6% 50%	4980
	21st to end	Day	14% 8% 3 7% 5% 4 4 3 5% 5% 41%	5462
April	1st to 10th	Day	12% 6% 2 7% 5% 5% 4 3 5% 6% 44%	2305
	11th to 20th	Day	16% 7% 2 6% 5% 4 4 4 5% 5% 42%	2374
	21st to end	Day	11% 5% 2 7% 5% 5% 5% 4 6% 6% 45%	2400
May	1st to 10th	Day	16% 8% 2 7% 5% 5% 4 4 6% 7% 36%	5405
	11th to 20th	Day	13% 6% 2 7% 5% 6% 5% 4 6% 7% 39%	5770
	21st to end	Day	10% 6% 3 6% 5% 5% 5% 4 7% 9% 40%	6434
June	1st to 10th	Day	7% 5% 2 6% 6% 6% 5% 5% 8% 9% 42%	2600
	11th to 20th	Day	5% 5% 2 6% 5% 6% 7% 5% 8% 9% 44%	2600
	21st to end	Day	5% 4 2 5% 6% 6% 5% 5% 8% 9% 46%	2600
July	1st to 10th	Day	8% 5% 2 6% 5% 6% 6% 5% 7% 11% 37%	4250
	11th to 20th	Day	7% 5% 2 6% 5% 6% 6% 5% 8% 10% 42%	4250
	21st to end	Day	17% 8% 3 7% 4 5% 5% 4 6% 8% 33%	4466
August	1st to 10th	Day	3 2 1 3 2 3 3 4 4 7% 68%	4104
	11th to 20th	Day	4 3 1 4 3 3 4 4 7% 11% 55%	3764
	21st to end	Day	8% 5% 2 6% 6% 6% 6% 4 7% 8% 42%	4180
September	1st to 10th	Day	8% 5% 3 6% 5% 6% 5% 4 6% 7% 47%	2280
	11th to 20th	Day	13% 6% 2 5% 5% 5% 5% 4 6% 7% 42%	2142
	21st to end	Day	8% 4 1 5% 4 4 4 4 6% 8% 54%	2044
October	1st to 10th	Day	7% 3 1 4 2 3 4 3 5% 6% 61%	1900
	11th to 20th	Day	12% 5% 2 5% 3 3 3 3 4 5% 56%	1900
	21st to end	Day	15% 5% 1 5% 3 2 3 3 3 4 55%	2090
November	1st to 10th	Day	12% 5% 2 6% 4 3 4 3 5% 6% 50%	1958
	11th to 20th	Day	11% 6% 2 5% 3 3 4 2 4 5% 54%	2000
	21st to end	Day	18% 6% 3 5% 4 4 4 2 4 5% 45%	1985
December	1st to 10th	Day	18% 6% 2 7% 3 3 3 2 4 5% 47%	2940
	11th to 20th	Day	18% 9% 3 6% 3 4 4 3 4 5% 40%	3391
	21st to end	Day	16% 9% 2 7% 4 4 3 3 4 5% 45%	4488
January	1st to 10th	Night	16% 6% 2 4 3 3 3 2 4 5% 53%	5888
	11th to 20th	Night	15% 5% 2 4 3 2 3 2 4 5% 54%	5900
	21st to end	Night	25% 9% 3 6% 3 3 3 2 3 3 40%	6490
February	1st to 10th	Night	17% 8% 3 5% 3 3 3 3 4 5% 46%	2600
	11th to 20th	Night	21% 9% 3 5% 4 2 3 2 4 4 43%	2387
	21st to end	Night	21% 7% 2 5% 4 2 3 2 3 5% 45%	1815
March	1st to 10th	Night	19% 7% 2 5% 4 3 4 3 5% 6% 40%	4919
	11th to 20th	Night	15% 5% 1 5% 3 3 4 3 5% 7% 48%	4980
	21st to end	Night	15% 6% 2 6% 5% 4 4 4 5% 6% 43%	5467
April	1st to 10th	Night	13% 5% 2 5% 3 3 4 4 6% 8% 47%	2092
	11th to 20th	Night	12% 6% 2 6% 4 3 4 3 5% 8% 47%	1975
	21st to end	Night	12% 5% 2 5% 5% 3 3 3 5% 8% 51%	2000
May	1st to 10th	Night	15% 8% 3 7% 5% 4 4 4 5% 7% 37%	4490
	11th to 20th	Night	14% 7% 3 7% 4 4 4 3 7% 8% 38%	4124
	21st to end	Night	11% 6% 2 5% 4 4 4 4 6% 10% 44%	4443
June	1st to 10th	Night	5% 4 2 4 4 5% 5% 4 6% 10% 51%	1800
	11th to 20th	Night	5% 4 2 4 5% 4 4 3 7% 10% 52%	1800
	21st to end	Night	6% 3 1 5% 4 4 4 4 7% 9% 54%	1800
July	1st to 10th	Night	7% 5% 2 5% 4 6% 5% 6% 8% 14% 39%	2940
	11th to 20th	Night	5% 3 2 5% 3 4 5% 4 9% 13% 47%	2940
	21st to end	Night	14% 8% 2 6% 4 4 3 3 5% 9% 41%	3098
August	1st to 10th	Night	2 1 1 2 2 2 3 3 5% 8% 72%	2836
	11th to 20th	Night	2 2 1 3 2 3 4 4 7% 13% 58%	3063
	21st to end	Night	6% 4 2 6% 4 5% 6% 5% 7% 9% 48%	3476
September	1st to 10th	Night	6% 6% 2 7% 4 4 4 4 6% 9% 50%	1900
	11th to 20th	Night	11% 5% 2 5% 4 4 4 3 5% 8% 49%	2033
	21st to end	Night	8% 3 2 4 3 3 3 3 5% 6% 59%	2114
October	1st to 10th	Night	7% 3 1 4 3 3 3 4 5% 6% 61%	2280
	11th to 20th	Night	10% 4 1 4 4 2 3 3 3 5% 60%	2280
	21st to end	Night	13% 4 2 4 3 3 3 2 4 4 59%	2508
November	1st to 10th	Night	12% 5% 1 4 4 3 3 2 3 6% 56%	2340
	11th to 20th	Night	11% 5% 2 5% 3 3 3 3 4 6% 55%	2400
	21st to end	Night	15% 6% 2 6% 4 3 3 2 5% 5% 49%	2410
December	1st to 10th	Night	18% 7% 2 5% 3 3 3 3 4 5% 47%	4250
	11th to 20th	Night	16% 7% 3 7% 5% 4 4 3 3 3 45%	4816
	21st to end	Night	15% 9% 2 5% 3 3 3 3 4 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	43% 3 6% 23% 22% 3	4078
	11th to 20th	Day	32% 4 5% 24% 25% 10%	4080
	21st to end	Day	46% 3 3 13% 20% 14%	4488
February	1st to 10th	Day	49% 4 6% 15% 17% 10%	1800
	11th to 20th	Day	49% 5% 6% 15% 18% 7%	1921
	21st to end	Day	49% 4 7% 11% 19% 10%	1815
March	1st to 10th	Day	50% 4 5% 12% 17% 11%	4936
	11th to 20th	Day	36% 4 5% 16% 22% 17%	4980
	21st to end	Day	44% 5% 8% 19% 19% 4	5464
April	1st to 10th	Day	41% 6% 9% 21% 16% 8%	2305
	11th to 20th	Day	42% 7% 8% 15% 19% 8%	2374
	21st to end	Day	36% 8% 10% 20% 22% 3	2400
May	1st to 10th	Day	45% 7% 11% 24% 11% 2	5440
	11th to 20th	Day	41% 7% 13% 19% 19% 2	5774
	21st to end	Day	38% 8% 13% 22% 16% 2	6447
June	1st to 10th	Day	35% 10% 15% 23% 16% 2	2600
	11th to 20th	Day	32% 10% 16% 22% 17% 3	2600
	21st to end	Day	30% 10% 15% 27% 15% 3	2600
July	1st to 10th	Day	39% 8% 22% 24% 6% 1	4186
	11th to 20th	Day	35% 8% 16% 29% 11% 1	4181
	21st to end	Day	48% 8% 14% 21% 9%	4326
August	1st to 10th	Day	15% 7% 14% 30% 29% 4	4090
	11th to 20th	Day	23% 6% 21% 37% 12% 1	3800
	21st to end	Day	37% 9% 15% 18% 20% 2	4179
September	1st to 10th	Day	35% 8% 13% 19% 17% 8%	2280
	11th to 20th	Day	39% 8% 12% 18% 17% 6%	2142
	21st to end	Day	29% 6% 11% 21% 24% 10%	2044
October	1st to 10th	Day	15% 4 6% 14% 24% 38%	3160
	11th to 20th	Day	19% 3 4 16% 31% 26%	3140
	21st to end	Day	27% 3 4 18% 35% 12%	3428
November	1st to 10th	Day	36% 5% 10% 17% 24% 9%	1958
	11th to 20th	Day	34% 3 6% 17% 28% 12%	2000
	21st to end	Day	43% 4 7% 17% 23% 8%	1985
December	1st to 10th	Day	41% 4 6% 19% 25% 5%	2940
	11th to 20th	Day	46% 5% 6% 14% 21% 9%	3389
	21st to end	Day	43% 4 5% 17% 27% 4	4488
January	1st to 10th	Night	35% 3 6% 24% 26% 5%	5888
	11th to 20th	Night	34% 4 4 18% 29% 10%	5900
	21st to end	Night	51% 3 5% 13% 18% 11%	6490
February	1st to 10th	Night	41% 5% 7% 17% 20% 11%	2600
	11th to 20th	Night	46% 4 6% 16% 20% 9%	2388
	21st to end	Night	44% 5% 7% 13% 16% 14%	1815
March	1st to 10th	Night	44% 5% 6% 12% 22% 11%	4919
	11th to 20th	Night	35% 6% 7% 15% 19% 18%	4980
	21st to end	Night	41% 7% 9% 17% 21% 6%	5467
April	1st to 10th	Night	35% 6% 10% 21% 17% 11%	2092
	11th to 20th	Night	36% 6% 9% 17% 20% 12%	1975
	21st to end	Night	32% 5% 11% 23% 25% 4	2000
May	1st to 10th	Night	44% 7% 11% 21% 13% 4	4520
	11th to 20th	Night	42% 6% 13% 19% 18% 2	4125
	21st to end	Night	34% 8% 16% 24% 14% 4	4452
June	1st to 10th	Night	26% 10% 15% 27% 20% 2	1800
	11th to 20th	Night	25% 9% 17% 27% 18% 5%	1800
	21st to end	Night	26% 6% 18% 26% 22% 3	1800
July	1st to 10th	Night	33% 10% 27% 24% 5% 1	2895
	11th to 20th	Night	27% 9% 22% 29% 12% 1	2886
	21st to end	Night	41% 7% 18% 23% 9% 1	2999
August	1st to 10th	Night	11% 6% 16% 32% 32% 4	2826
	11th to 20th	Night	18% 7% 20% 42% 12% 2	3093
	21st to end	Night	30% 8% 15% 23% 22% 2	3476
September	1st to 10th	Night	29% 8% 15% 21% 16% 11%	1900
	11th to 20th	Night	34% 7% 10% 20% 19% 10%	2033
	21st to end	Night	25% 6% 11% 20% 26% 12%	2114
October	1st to 10th	Night	14% 4 5% 13% 21% 42%	3800
	11th to 20th	Night	16% 3 5% 16% 31% 29%	3779
	21st to end	Night	24% 3 5% 15% 37% 16%	4120
November	1st to 10th	Night	32% 4 9% 17% 26% 12%	2340
	11th to 20th	Night	32% 4 8% 17% 25% 15%	2400
	21st to end	Night	38% 4 8% 17% 24% 10%	2410
December	1st to 10th	Night	42% 4 6% 18% 26% 5%	4250
	11th to 20th	Night	44% 4 7% 13% 22% 9%	4817
	21st to end	Night	39% 4 5% 19% 28% 5%	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	23% 9% 37% 20% 10% 1	300
	11th to 20th	Day	26% 10% 34% 20% 8% 1	300
	21st to end	Day	23% 13% 36% 22% 5%	330
February	1st to 10th	Day	26% 12% 30% 25% 7% 1	300
	11th to 20th	Day	29% 13% 33% 21% 4	300
	21st to end	Day	32% 13% 35% 15% 5%	249
March	1st to 10th	Day	23% 15% 33% 19% 9% 1	300
	11th to 20th	Day	20% 16% 35% 24% 4 1	300
	21st to end	Day	17% 13% 41% 21% 6% 1	330
April	1st to 10th	Day	18% 13% 33% 26% 10%	405
	11th to 20th	Day	22% 9% 29% 26% 12% 1	492
	21st to end	Day	15% 8% 26% 33% 15% 3	500
May	1st to 10th	Day	15% 8% 30% 32% 14% 1	503
	11th to 20th	Day	15% 5% 21% 32% 23% 5%	685
	21st to end	Day	11% 3 20% 34% 27% 6%	789
June	1st to 10th	Day	8% 2 9% 33% 34% 14%	730
	11th to 20th	Day	5% 2 11% 32% 39% 12%	730
	21st to end	Day	7% 1 8% 24% 38% 22%	730
July	1st to 10th	Day	9% 1 5% 21% 41% 22%	721
	11th to 20th	Day	5% 2 5% 19% 41% 28%	718
	21st to end	Day	8% 1 4 21% 44% 22%	740
August	1st to 10th	Day	5% 1 3 16% 46% 29%	676
	11th to 20th	Day	8% 1 2 13% 46% 30%	502
	21st to end	Day	13% 2 2 14% 35% 33%	539
September	1st to 10th	Day	8% 1 6% 17% 42% 26%	490
	11th to 20th	Day	11% 2 7% 20% 34% 26%	352
	21st to end	Day	8% 3 8% 22% 37% 22%	300
October	1st to 10th	Day	8% 14% 31% 32% 15%	300
	11th to 20th	Day	10% 5% 23% 33% 21% 8%	300
	21st to end	Day	20% 8% 21% 27% 17% 8%	330
November	1st to 10th	Day	14% 5% 27% 26% 23% 4	300
	11th to 20th	Day	12% 10% 26% 34% 15% 3	300
	21st to end	Day	17% 12% 31% 26% 13% 2	300
December	1st to 10th	Day	20% 6% 36% 25% 11% 2	300
	11th to 20th	Day	22% 11% 30% 25% 10% 1	300
	21st to end	Day	22% 12% 33% 24% 7% 2	330
January	1st to 10th	Night	21% 6% 30% 35% 7%	1000
	11th to 20th	Night	22% 7% 32% 31% 9%	1000
	21st to end	Night	23% 5% 32% 35% 4	1100
February	1st to 10th	Night	21% 7% 31% 35% 5%	1000
	11th to 20th	Night	25% 7% 32% 31% 5%	832
	21st to end	Night	24% 8% 36% 28% 4	495
March	1st to 10th	Night	19% 7% 29% 38% 7%	600
	11th to 20th	Night	18% 7% 31% 37% 7% 1	600
	21st to end	Night	16% 5% 35% 37% 6%	660
April	1st to 10th	Night	15% 8% 35% 34% 9%	600
	11th to 20th	Night	16% 8% 32% 33% 11% 1	593
	21st to end	Night	13% 4 37% 32% 13% 1	600
May	1st to 10th	Night	11% 5% 29% 41% 13% 1	600
	11th to 20th	Night	13% 4 22% 41% 18% 2	591
	21st to end	Night	9% 2 16% 45% 24% 4	650
June	1st to 10th	Night	6% 2 9% 43% 37% 5%	600
	11th to 20th	Night	5% 2 9% 40% 40% 4	600
	21st to end	Night	6% 1 7% 33% 45% 9%	600
July	1st to 10th	Night	5% 1 2 30% 52% 10%	585
	11th to 20th	Night	5% 1 3 28% 53% 11%	582
	21st to end	Night	6% 1 4 25% 53% 10%	624
August	1st to 10th	Night	3 1 2 22% 61% 11%	567
	11th to 20th	Night	5% 1 2 27% 57% 8%	564
	21st to end	Night	10% 3 24% 50% 12%	627
September	1st to 10th	Night	7% 3 3 29% 48% 10%	570
	11th to 20th	Night	12% 2 4 29% 46% 8%	570
	21st to end	Night	9% 2 6% 33% 43% 7%	594
October	1st to 10th	Night	8% 2 7% 41% 38% 5%	760
	11th to 20th	Night	12% 3 17% 41% 26% 2	760
	21st to end	Night	14% 4 20% 40% 20% 3	836
November	1st to 10th	Night	15% 2 21% 38% 22% 2	780
	11th to 20th	Night	13% 5% 23% 43% 16% 1	800
	21st to end	Night	17% 6% 27% 35% 13% 1	810
December	1st to 10th	Night	20% 6% 23% 40% 10%	1000
	11th to 20th	Night	20% 6% 28% 38% 8%	1000
	21st to end	Night	20% 7% 29% 34% 9% 1	1100

Page generated at 2025-07-18 00:09:58. Version ac07

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