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 2024-03-28.

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 5% 5% 3 5% 5% 5% 7% 44%	79296
	Night	13% 5% 2 4 4 3 4 4 5% 7% 50%	80751
Transparency	Day	38% 7% 11% 20% 19% 6%	79020
	Night	34% 6% 11% 20% 21% 8%	80547
Seeing	Day	13% 5% 18% 25% 26% 13%	14203
	Night	14% 4 21% 35% 23% 3	24190

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% 4 2 3 3 4 5% 41%	2847
	11th to 20th	Day	21% 6% 1 4 3 2 3 3 3 5% 48%	2850
	21st to end	Day	23% 8% 2 5% 3 2 3 3 4 5% 43%	3135
February	1st to 10th	Day	21% 10% 3 5% 5% 3 3 4 4 4 39%	1710
	11th to 20th	Day	22% 8% 3 4 4 3 4 4 3 5% 40%	1813
	21st to end	Day	23% 8% 2 5% 6% 2 3 3 4 4 39%	1727
March	1st to 10th	Day	19% 8% 3 6% 5% 3 4 4 4 6% 38%	2090
	11th to 20th	Day	19% 6% 4 5% 5% 3 5% 3 6% 6% 39%	2090
	21st to end	Day	15% 7% 4 6% 5% 2 4 4 5% 6% 43%	2255
April	1st to 10th	Day	12% 6% 3 6% 6% 4 5% 4 4 7% 45%	2074
	11th to 20th	Day	16% 7% 2 5% 5% 3 5% 5% 5% 6% 41%	2134
	21st to end	Day	11% 5% 2 6% 5% 3 4 5% 6% 6% 46%	2160
May	1st to 10th	Day	11% 7% 3 6% 5% 3 4 5% 6% 7% 43%	2160
	11th to 20th	Day	11% 5% 2 6% 5% 4 6% 6% 6% 8% 41%	2266
	21st to end	Day	10% 4 3 5% 7% 4 7% 7% 6% 9% 40%	2531
June	1st to 10th	Day	7% 5% 2 6% 6% 4 7% 5% 8% 8% 42%	2340
	11th to 20th	Day	5% 3 3 5% 5% 4 7% 7% 8% 10% 44%	2340
	21st to end	Day	6% 4 2 5% 7% 5% 6% 6% 8% 9% 44%	2340
July	1st to 10th	Day	9% 4 3 5% 6% 5% 6% 7% 7% 11% 36%	2340
	11th to 20th	Day	6% 4 2 5% 5% 5% 6% 7% 8% 9% 43%	2340
	21st to end	Day	7% 4 3 5% 5% 4 7% 8% 7% 11% 40%	2546
August	1st to 10th	Day	4 3 2 4 5% 3 6% 7% 7% 10% 50%	2328
	11th to 20th	Day	7% 4 1 5% 5% 3 6% 6% 7% 11% 44%	2147
	21st to end	Day	11% 5% 2 5% 7% 4 6% 6% 7% 9% 39%	2376
September	1st to 10th	Day	7% 5% 3 4 6% 4 6% 5% 6% 7% 47%	2160
	11th to 20th	Day	13% 5% 3 5% 5% 3 5% 6% 6% 7% 42%	2030
	21st to end	Day	8% 4 1 4 4 3 4 5% 5% 8% 54%	1937
October	1st to 10th	Day	7% 4 1 3 3 3 3 4 5% 7% 60%	1800
	11th to 20th	Day	13% 5% 2 4 4 2 3 4 4 5% 54%	1800
	21st to end	Day	16% 5% 1 4 4 2 3 3 3 4 54%	1980
November	1st to 10th	Day	11% 5% 2 5% 4 3 4 3 5% 6% 53%	1858
	11th to 20th	Day	11% 6% 3 5% 4 2 4 3 4 5% 53%	1900
	21st to end	Day	19% 6% 3 5% 5% 3 4 3 4 5% 44%	1886
December	1st to 10th	Day	15% 8% 2 6% 4 3 3 4 4 6% 44%	1710
	11th to 20th	Day	16% 9% 4 5% 4 2 5% 4 4 6% 41%	2161
	21st to end	Day	15% 9% 3 7% 5% 3 4 4 4 5% 41%	3135
January	1st to 10th	Night	15% 8% 2 5% 4 2 3 3 4 5% 48%	4108
	11th to 20th	Night	20% 5% 2 4 3 2 3 3 3 4 52%	4120
	21st to end	Night	24% 8% 2 5% 4 2 3 2 3 4 43%	4532
February	1st to 10th	Night	17% 7% 3 4 4 2 3 4 5% 5% 46%	2470
	11th to 20th	Night	20% 8% 3 4 4 2 3 3 4 5% 45%	2265
	21st to end	Night	21% 7% 2 4 4 2 4 3 3 5% 45%	1727
March	1st to 10th	Night	17% 5% 2 4 5% 3 4 4 4 6% 44%	2090
	11th to 20th	Night	18% 5% 2 6% 4 3 5% 5% 5% 6% 41%	2090
	21st to end	Night	13% 4 2 4 5% 3 4 5% 5% 7% 48%	2255
April	1st to 10th	Night	11% 4 2 5% 4 2 4 5% 6% 9% 48%	1884
	11th to 20th	Night	12% 5% 2 5% 5% 2 4 4 5% 8% 47%	1775
	21st to end	Night	11% 4 3 4 5% 3 3 4 4 9% 52%	1800
May	1st to 10th	Night	9% 6% 3 4 5% 3 4 5% 6% 9% 48%	1800
	11th to 20th	Night	11% 4 2 5% 4 3 4 3 6% 9% 49%	1625
	21st to end	Night	8% 5% 3 4 4 3 4 4 6% 10% 50%	1745
June	1st to 10th	Night	5% 4 1 4 4 3 5% 5% 6% 11% 52%	1620
	11th to 20th	Night	5% 3 1 3 4 3 4 4 7% 11% 55%	1620
	21st to end	Night	6% 3 2 4 4 3 5% 4 7% 9% 53%	1620
July	1st to 10th	Night	6% 4 3 4 4 4 5% 6% 7% 13% 44%	1620
	11th to 20th	Night	4 2 1 3 3 3 4 5% 8% 13% 54%	1620
	21st to end	Night	3 3 2 4 4 3 4 6% 7% 12% 51%	1772
August	1st to 10th	Night	2 2 1 2 3 2 4 6% 6% 11% 60%	1611
	11th to 20th	Night	4 4 2 3 4 3 4 6% 7% 11% 52%	1751
	21st to end	Night	8% 3 2 5% 5% 4 6% 5% 7% 10% 45%	1980
September	1st to 10th	Night	6% 5% 2 5% 5% 3 4 5% 6% 8% 52%	1800
	11th to 20th	Night	10% 4 2 4 5% 3 4 4 5% 8% 49%	1926
	21st to end	Night	9% 3 2 4 3 2 3 4 5% 6% 59%	2002
October	1st to 10th	Night	7% 3 2 3 4 3 3 5% 5% 7% 59%	2160
	11th to 20th	Night	11% 4 2 4 4 2 3 4 3 5% 58%	2160
	21st to end	Night	14% 4 2 4 3 2 3 3 4 4 58%	2376
November	1st to 10th	Night	11% 5% 1 4 3 3 3 3 3 5% 59%	2220
	11th to 20th	Night	11% 5% 2 5% 4 2 4 4 4 6% 54%	2280
	21st to end	Night	16% 5% 3 5% 5% 2 4 2 5% 5% 48%	2289
December	1st to 10th	Night	16% 7% 3 4 4 2 3 4 4 7% 45%	2470
	11th to 20th	Night	14% 7% 3 6% 5% 3 4 4 4 4 48%	3036
	21st to end	Night	16% 7% 2 4 4 3 3 4 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	47% 6% 8% 14% 17% 8%	2090
	11th to 20th	Day	46% 5% 7% 18% 19% 5%	2090
	21st to end	Day	43% 5% 8% 16% 24% 4	2255
April	1st to 10th	Day	40% 6% 9% 22% 16% 7%	2074
	11th to 20th	Day	43% 7% 9% 16% 18% 8%	2134
	21st to end	Day	36% 8% 10% 21% 22% 3	2160
May	1st to 10th	Day	40% 7% 10% 20% 18% 6%	2160
	11th to 20th	Day	37% 9% 12% 25% 14% 3	2270
	21st to end	Day	38% 9% 14% 23% 15% 1	2531
June	1st to 10th	Day	36% 10% 15% 23% 14% 2	2340
	11th to 20th	Day	32% 10% 17% 23% 16% 2	2340
	21st to end	Day	33% 11% 14% 25% 15% 3	2340
July	1st to 10th	Day	39% 11% 19% 23% 8% 1	2276
	11th to 20th	Day	31% 12% 19% 26% 11% 1	2271
	21st to end	Day	34% 12% 20% 23% 10% 1	2405
August	1st to 10th	Day	25% 12% 20% 27% 14% 1	2314
	11th to 20th	Day	32% 9% 18% 25% 15% 1	2147
	21st to end	Day	37% 12% 17% 20% 12% 2	2376
September	1st to 10th	Day	34% 8% 13% 20% 17% 7%	2160
	11th to 20th	Day	39% 8% 12% 18% 16% 6%	2030
	21st to end	Day	29% 6% 11% 21% 23% 10%	1937
October	1st to 10th	Day	24% 5% 11% 23% 23% 13%	1800
	11th to 20th	Day	32% 5% 6% 18% 26% 13%	1800
	21st to end	Day	35% 4 5% 16% 28% 12%	1980
November	1st to 10th	Day	33% 5% 10% 18% 25% 10%	1858
	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	41% 5% 8% 16% 20% 10%	2090
	11th to 20th	Night	42% 7% 9% 15% 19% 8%	2090
	21st to end	Night	36% 7% 9% 17% 25% 6%	2255
April	1st to 10th	Night	33% 6% 11% 22% 17% 10%	1884
	11th to 20th	Night	36% 6% 10% 18% 19% 12%	1775
	21st to end	Night	31% 5% 11% 23% 26% 4	1800
May	1st to 10th	Night	34% 7% 13% 20% 17% 10%	1800
	11th to 20th	Night	32% 6% 12% 26% 20% 4	1626
	21st to end	Night	30% 8% 16% 26% 20% 1	1746
June	1st to 10th	Night	25% 11% 15% 27% 20% 1	1620
	11th to 20th	Night	22% 9% 18% 29% 19% 4	1620
	21st to end	Night	27% 7% 17% 24% 23% 3	1620
July	1st to 10th	Night	29% 11% 25% 26% 8% 1	1575
	11th to 20th	Night	19% 10% 27% 26% 15% 2	1566
	21st to end	Night	22% 11% 27% 25% 13% 1	1673
August	1st to 10th	Night	16% 9% 23% 34% 16% 1	1601
	11th to 20th	Night	24% 11% 20% 25% 16% 4	1751
	21st to end	Night	31% 11% 17% 24% 15% 3	1980
September	1st to 10th	Night	28% 8% 16% 22% 17% 10%	1800
	11th to 20th	Night	34% 7% 11% 20% 19% 10%	1926
	21st to end	Night	25% 6% 11% 20% 25% 13%	2002
October	1st to 10th	Night	24% 6% 9% 23% 23% 16%	2160
	11th to 20th	Night	28% 5% 7% 14% 29% 16%	2160
	21st to end	Night	31% 4 6% 16% 27% 16%	2376
November	1st to 10th	Night	29% 4 9% 17% 28% 13%	2220
	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	19% 12% 40% 22% 6% 1	285
April	1st to 10th	Day	16% 10% 35% 28% 10% 1	334
	11th to 20th	Day	23% 7% 27% 27% 14% 2	412
	21st to end	Day	16% 7% 26% 35% 14% 2	420
May	1st to 10th	Day	13% 7% 28% 34% 17% 1	423
	11th to 20th	Day	14% 3 19% 34% 25% 5%	589
	21st to end	Day	11% 3 16% 34% 30% 7%	679
June	1st to 10th	Day	9% 1 6% 33% 35% 15%	630
	11th to 20th	Day	4 1 10% 30% 41% 12%	630
	21st to end	Day	8% 1 9% 25% 35% 22%	630
July	1st to 10th	Day	9% 1 5% 22% 39% 23%	621
	11th to 20th	Day	5% 1 5% 18% 41% 30%	618
	21st to end	Day	5% 1 3 21% 45% 24%	684
August	1st to 10th	Day	6% 1 3 16% 45% 30%	626
	11th to 20th	Day	8% 1 2 13% 47% 30%	461
	21st to end	Day	13% 2 2 13% 35% 34%	495
September	1st to 10th	Day	7% 1 4 16% 44% 29%	450
	11th to 20th	Day	10% 2 7% 19% 34% 27%	320
	21st to end	Day	8% 3 4 23% 39% 24%	270
October	1st to 10th	Day	9% 13% 29% 32% 17%	270
	11th to 20th	Day	11% 4 22% 31% 21% 9%	270
	21st to end	Day	21% 8% 23% 25% 15% 7%	297
November	1st to 10th	Day	12% 4 26% 28% 26% 4	270
	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% 5% 36% 37% 7%	615
April	1st to 10th	Night	13% 6% 37% 35% 9%	540
	11th to 20th	Night	15% 7% 32% 34% 12% 1	533
	21st to end	Night	12% 5% 37% 33% 13% 1	540
May	1st to 10th	Night	10% 4 30% 41% 14% 1	540
	11th to 20th	Night	12% 2 21% 43% 19% 2	531
	21st to end	Night	8% 2 15% 44% 27% 5%	584
June	1st to 10th	Night	6% 1 7% 43% 38% 5%	540
	11th to 20th	Night	5% 1 8% 41% 41% 4	540
	21st to end	Night	6% 1 7% 32% 44% 9%	540
July	1st to 10th	Night	5% 1 2 31% 51% 10%	525
	11th to 20th	Night	4 1 2 29% 54% 11%	522
	21st to end	Night	4 1 5% 25% 54% 11%	591
August	1st to 10th	Night	3 1 2 22% 61% 12%	537
	11th to 20th	Night	5% 1 1 27% 57% 9%	534
	21st to end	Night	10% 1 3 23% 51% 12%	594
September	1st to 10th	Night	7% 3 3 28% 50% 10%	540
	11th to 20th	Night	11% 2 4 28% 47% 8%	540
	21st to end	Night	9% 2 6% 32% 43% 7%	562
October	1st to 10th	Night	8% 2 7% 39% 38% 5%	720
	11th to 20th	Night	12% 3 17% 40% 26% 2	720
	21st to end	Night	15% 4 20% 39% 20% 3	792
November	1st to 10th	Night	14% 2 20% 39% 23% 2	740
	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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