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 2024-11-04.

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% 44%	100995
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 48%	98077
Transparency	Day	37% 6% 11% 20% 19% 6%	104640
	Night	33% 6% 11% 20% 21% 9%	102572
Seeing	Day	13% 5% 18% 25% 26% 13%	15118
	Night	14% 4 21% 35% 23% 3	24892

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	19% 11% 3 5% 3 3 3 2 4 5% 41%	2847
	11th to 20th	Day	21% 7% 1 4 3 3 3 3 3 5% 48%	2850
	21st to end	Day	23% 8% 2 5% 3 3 2 2 4 4 43%	3135
February	1st to 10th	Day	21% 10% 3 6% 4 4 2 3 4 4 39%	1710
	11th to 20th	Day	22% 8% 2 5% 4 3 5% 3 3 5% 39%	1813
	21st to end	Day	23% 8% 2 6% 5% 3 2 3 4 4 39%	1727
March	1st to 10th	Day	19% 12% 3 10% 5% 4 4 3 4 5% 32%	3436
	11th to 20th	Day	20% 7% 3 6% 4 4 4 3 6% 7% 37%	3480
	21st to end	Day	16% 9% 3 7% 4 4 3 3 5% 5% 41%	3814
April	1st to 10th	Day	12% 6% 2 7% 5% 5% 4 3 5% 6% 44%	2190
	11th to 20th	Day	16% 7% 2 6% 5% 4 4 4 5% 6% 40%	2254
	21st to end	Day	11% 5% 2 7% 4 5% 5% 4 6% 6% 45%	2280
May	1st to 10th	Day	16% 8% 2 7% 6% 5% 4 4 6% 7% 35%	3765
	11th to 20th	Day	13% 6% 2 6% 4 5% 5% 3 5% 7% 44%	4018
	21st to end	Day	12% 6% 3 6% 6% 5% 5% 5% 7% 8% 37%	4477
June	1st to 10th	Day	7% 5% 2 7% 5% 6% 5% 5% 8% 8% 42%	2470
	11th to 20th	Day	5% 4 2 6% 5% 6% 7% 6% 8% 9% 44%	2470
	21st to end	Day	5% 5% 2 5% 6% 6% 6% 5% 8% 9% 44%	2470
July	1st to 10th	Day	9% 5% 2 6% 5% 6% 6% 5% 7% 11% 38%	4120
	11th to 20th	Day	7% 5% 2 7% 5% 6% 6% 5% 8% 9% 41%	4120
	21st to end	Day	17% 8% 3 7% 4 5% 5% 4 6% 8% 33%	4465
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	11% 5% 2 6% 4 3 4 2 5% 6% 52%	1888
	11th to 20th	Day	11% 6% 3 5% 3 3 4 2 4 5% 53%	1900
	21st to end	Day	19% 6% 3 5% 5% 3 4 2 4 5% 44%	1886
December	1st to 10th	Day	15% 8% 2 6% 4 3 3 3 4 6% 44%	1710
	11th to 20th	Day	16% 10% 3 5% 3 4 4 3 4 6% 41%	2161
	21st to end	Day	15% 9% 3 8% 4 4 4 3 4 5% 41%	3135
January	1st to 10th	Night	15% 8% 2 6% 3 3 3 2 4 5% 48%	4108
	11th to 20th	Night	19% 5% 2 4 3 2 3 2 3 4 52%	4120
	21st to end	Night	24% 8% 2 6% 3 2 2 2 3 4 43%	4532
February	1st to 10th	Night	17% 8% 3 5% 3 3 4 3 5% 5% 46%	2470
	11th to 20th	Night	20% 8% 3 5% 4 2 3 2 4 5% 45%	2265
	21st to end	Night	21% 7% 2 5% 4 2 3 2 3 5% 45%	1727
March	1st to 10th	Night	21% 8% 3 6% 5% 4 4 3 5% 6% 36%	3419
	11th to 20th	Night	19% 7% 2 7% 4 4 5% 4 6% 6% 37%	3480
	21st to end	Night	12% 5% 2 6% 5% 4 4 5% 6% 7% 43%	3817
April	1st to 10th	Night	12% 5% 2 5% 4 3 4 4 6% 8% 47%	1988
	11th to 20th	Night	12% 6% 2 6% 4 3 5% 3 5% 8% 46%	1875
	21st to end	Night	11% 5% 2 5% 4 3 3 3 4 9% 51%	1900
May	1st to 10th	Night	13% 8% 3 6% 5% 4 4 4 6% 8% 39%	3130
	11th to 20th	Night	14% 6% 3 7% 4 3 3 3 6% 8% 43%	2868
	21st to end	Night	11% 6% 2 5% 4 4 4 4 6% 9% 43%	3090
June	1st to 10th	Night	5% 4 1 4 3 5% 5% 4 6% 11% 51%	1710
	11th to 20th	Night	5% 4 2 3 4 4 4 3 7% 10% 54%	1710
	21st to end	Night	6% 3 1 5% 4 4 4 4 7% 9% 53%	1710
July	1st to 10th	Night	7% 5% 2 5% 4 6% 5% 6% 8% 14% 40%	2850
	11th to 20th	Night	6% 3 1 5% 3 4 5% 4 9% 13% 47%	2850
	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	11% 5% 1 4 4 3 3 2 3 5% 58%	2263
	11th to 20th	Night	11% 5% 2 5% 3 3 3 3 4 6% 54%	2280
	21st to end	Night	16% 6% 2 6% 4 3 3 2 5% 5% 48%	2289
December	1st to 10th	Night	16% 8% 2 5% 3 3 3 4 4 6% 45%	2470
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 4 4 47%	3036
	21st to end	Night	16% 7% 2 5% 4 4 3 3 4 4 48%	4532

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	45% 4 5% 15% 26% 4	2848
	11th to 20th	Day	39% 5% 7% 23% 21% 5%	2850
	21st to end	Day	44% 4 4 17% 20% 10%	3135
February	1st to 10th	Day	49% 4 6% 15% 15% 10%	1710
	11th to 20th	Day	48% 5% 6% 15% 19% 7%	1822
	21st to end	Day	49% 5% 7% 11% 19% 10%	1727
March	1st to 10th	Day	54% 6% 7% 12% 16% 5%	3436
	11th to 20th	Day	46% 6% 7% 20% 16% 5%	3480
	21st to end	Day	45% 5% 7% 17% 23% 2	3814
April	1st to 10th	Day	41% 6% 9% 21% 16% 8%	2190
	11th to 20th	Day	43% 7% 9% 15% 18% 8%	2254
	21st to end	Day	36% 8% 10% 20% 22% 4	2280
May	1st to 10th	Day	45% 9% 10% 22% 10% 3	3800
	11th to 20th	Day	37% 8% 10% 21% 22% 2	4022
	21st to end	Day	40% 10% 14% 23% 11% 2	4489
June	1st to 10th	Day	36% 10% 15% 23% 15% 2	2470
	11th to 20th	Day	32% 10% 16% 22% 17% 3	2470
	21st to end	Day	32% 11% 14% 26% 15% 3	2470
July	1st to 10th	Day	39% 8% 22% 25% 5% 1	4056
	11th to 20th	Day	35% 8% 16% 28% 12% 1	4051
	21st to end	Day	48% 8% 14% 21% 9%	4325
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	34% 5% 10% 18% 24% 10%	1888
	11th to 20th	Day	35% 4 6% 17% 28% 11%	1900
	21st to end	Day	44% 4 7% 17% 22% 7%	1886
December	1st to 10th	Day	41% 6% 10% 17% 19% 8%	1710
	11th to 20th	Day	44% 6% 6% 14% 25% 6%	2159
	21st to end	Day	45% 5% 6% 14% 25% 5%	3135
January	1st to 10th	Night	39% 5% 5% 16% 29% 7%	4108
	11th to 20th	Night	37% 5% 5% 20% 24% 8%	4120
	21st to end	Night	47% 3 6% 15% 19% 9%	4532
February	1st to 10th	Night	41% 5% 7% 17% 20% 10%	2470
	11th to 20th	Night	44% 4 6% 16% 21% 9%	2266
	21st to end	Night	44% 5% 7% 13% 16% 14%	1727
March	1st to 10th	Night	48% 6% 8% 14% 17% 7%	3419
	11th to 20th	Night	44% 8% 9% 14% 19% 5%	3480
	21st to end	Night	37% 9% 10% 16% 24% 4	3817
April	1st to 10th	Night	34% 6% 11% 21% 17% 11%	1988
	11th to 20th	Night	36% 6% 10% 18% 18% 12%	1875
	21st to end	Night	31% 5% 11% 23% 26% 4	1900
May	1st to 10th	Night	40% 10% 12% 20% 14% 5%	3160
	11th to 20th	Night	37% 8% 11% 22% 20% 3	2869
	21st to end	Night	34% 11% 15% 24% 14% 1	3099
June	1st to 10th	Night	26% 11% 15% 27% 20% 1	1710
	11th to 20th	Night	23% 8% 17% 28% 19% 5%	1710
	21st to end	Night	26% 7% 16% 26% 22% 3	1710
July	1st to 10th	Night	33% 10% 27% 24% 5% 1	2805
	11th to 20th	Night	26% 9% 22% 29% 13% 1	2796
	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	30% 4 9% 17% 27% 13%	2263
	11th to 20th	Night	32% 4 8% 17% 25% 13%	2280
	21st to end	Night	39% 4 7% 17% 24% 9%	2289
December	1st to 10th	Night	40% 5% 9% 19% 19% 8%	2470
	11th to 20th	Night	40% 5% 7% 12% 25% 11%	3037
	21st to end	Night	39% 5% 6% 18% 26% 6%	4532

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	22% 9% 36% 21% 11% 1	270
	11th to 20th	Day	27% 10% 33% 21% 9% 1	270
	21st to end	Day	22% 12% 37% 22% 6%	297
February	1st to 10th	Day	26% 12% 29% 25% 7% 1	270
	11th to 20th	Day	28% 11% 34% 23% 5%	270
	21st to end	Day	35% 13% 36% 15% 2	225
March	1st to 10th	Day	21% 14% 34% 20% 9% 1	270
	11th to 20th	Day	20% 14% 34% 27% 4 1	270
	21st to end	Day	18% 12% 41% 22% 6% 1	297
April	1st to 10th	Day	17% 12% 34% 27% 9% 1	370
	11th to 20th	Day	24% 8% 27% 26% 13% 2	452
	21st to end	Day	15% 8% 26% 33% 15% 3	460
May	1st to 10th	Day	14% 7% 30% 33% 15% 1	463
	11th to 20th	Day	14% 3 20% 33% 24% 5%	637
	21st to end	Day	11% 3 19% 33% 28% 6%	734
June	1st to 10th	Day	9% 1 8% 33% 35% 14%	680
	11th to 20th	Day	4 2 10% 31% 40% 12%	680
	21st to end	Day	7% 1 9% 25% 36% 22%	680
July	1st to 10th	Day	9% 1 6% 22% 40% 23%	671
	11th to 20th	Day	5% 2 6% 19% 40% 28%	668
	21st to end	Day	8% 1 4 21% 44% 22%	739
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	13% 4 27% 28% 25% 4	279
	11th to 20th	Day	13% 9% 28% 31% 16% 3	270
	21st to end	Day	19% 12% 29% 26% 12% 2	270
December	1st to 10th	Day	20% 6% 33% 27% 12% 3	270
	11th to 20th	Day	22% 11% 30% 26% 10% 1	270
	21st to end	Day	21% 12% 33% 25% 7% 2	297
January	1st to 10th	Night	21% 6% 30% 35% 8%	950
	11th to 20th	Night	23% 6% 31% 31% 9%	950
	21st to end	Night	23% 5% 32% 35% 5%	1045
February	1st to 10th	Night	21% 7% 31% 35% 5%	950
	11th to 20th	Night	25% 6% 33% 32% 5%	790
	21st to end	Night	25% 8% 37% 26% 3	471
March	1st to 10th	Night	19% 6% 29% 39% 7%	570
	11th to 20th	Night	18% 5% 31% 38% 8% 1	570
	21st to end	Night	16% 4 36% 37% 6%	627
April	1st to 10th	Night	14% 7% 36% 35% 9%	570
	11th to 20th	Night	15% 7% 32% 33% 11% 1	563
	21st to end	Night	13% 5% 36% 33% 13% 1	570
May	1st to 10th	Night	10% 4 31% 41% 13% 1	570
	11th to 20th	Night	12% 3 21% 42% 19% 2	561
	21st to end	Night	8% 2 17% 44% 25% 4	617
June	1st to 10th	Night	6% 1 8% 43% 38% 5%	570
	11th to 20th	Night	5% 2 9% 40% 40% 4	570
	21st to end	Night	6% 1 7% 33% 44% 9%	570
July	1st to 10th	Night	6% 1 2 30% 52% 10%	555
	11th to 20th	Night	5% 1 3 28% 53% 10%	552
	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	14% 2 20% 39% 23% 2	755
	11th to 20th	Night	13% 4 23% 42% 17% 1	760
	21st to end	Night	18% 5% 27% 34% 14% 2	769
December	1st to 10th	Night	20% 5% 23% 40% 11%	950
	11th to 20th	Night	20% 6% 27% 38% 9%	950
	21st to end	Night	20% 7% 29% 34% 9% 1	1045

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