Baton Rouge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Baton Rouge clear sky chart from 2005-11-06 to 2026-08-15.

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	11% 6% 3 7% 5% 5% 5% 5% 6% 8% 38%	142572
	Night	12% 6% 2 6% 4 4 4 4 6% 8% 44%	139498
Transparency	Day	40% 7% 13% 18% 16% 6%	146186
	Night	37% 6% 13% 18% 17% 8%	143964
Seeing	Day	13% 7% 19% 24% 23% 14%	17215
	Night	14% 6% 20% 31% 24% 5%	26835

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% 8% 4 8% 4 4 4 3 4 6% 39%	5289
	11th to 20th	Day	11% 7% 3 6% 4 4 4 3 4 6% 50%	5310
	21st to end	Day	21% 8% 3 7% 4 4 5% 3 4 5% 35%	5940
February	1st to 10th	Day	15% 9% 3 7% 6% 4 3 3 5% 6% 39%	2100
	11th to 20th	Day	17% 7% 3 6% 4 4 5% 4 5% 6% 40%	2048
	21st to end	Day	17% 8% 3 7% 4 5% 4 3 5% 7% 37%	1738
March	1st to 10th	Day	19% 9% 3 8% 4 4 4 4 5% 6% 33%	5046
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 4 6% 7% 44%	5090
	21st to end	Day	14% 7% 3 7% 5% 5% 4 3 5% 7% 41%	5712
April	1st to 10th	Day	12% 7% 2 6% 5% 5% 5% 5% 6% 7% 40%	2520
	11th to 20th	Day	13% 7% 3 6% 5% 4 5% 4 7% 9% 39%	2494
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 4 7% 8% 43%	2520
May	1st to 10th	Day	19% 7% 2 7% 5% 5% 5% 4 6% 8% 31%	7021
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 7% 8% 42%	7031
	21st to end	Day	7% 6% 3 8% 6% 7% 6% 5% 8% 12% 32%	7736
June	1st to 10th	Day	7% 5% 3 7% 6% 7% 6% 5% 9% 9% 34%	2662
	11th to 20th	Day	5% 5% 2 8% 8% 8% 8% 7% 8% 8% 32%	2730
	21st to end	Day	6% 5% 3 8% 8% 8% 9% 7% 8% 10% 29%	2730
July	1st to 10th	Day	4 5% 2 8% 7% 8% 9% 7% 10% 11% 30%	7680
	11th to 20th	Day	6% 5% 3 8% 6% 7% 8% 6% 9% 12% 30%	7680
	21st to end	Day	6% 5% 3 8% 6% 6% 6% 6% 9% 14% 30%	8041
August	1st to 10th	Day	3 3 1 5% 4 5% 6% 4 7% 10% 52%	4025
	11th to 20th	Day	6% 4 2 6% 6% 6% 7% 6% 9% 11% 38%	3897
	21st to end	Day	10% 6% 3 9% 6% 6% 6% 4 7% 7% 34%	4312
September	1st to 10th	Day	10% 6% 3 6% 6% 7% 6% 6% 8% 9% 34%	2400
	11th to 20th	Day	11% 6% 3 7% 5% 6% 5% 4 6% 9% 40%	2400
	21st to end	Day	9% 5% 2 6% 4 4 5% 5% 5% 7% 48%	2182
October	1st to 10th	Day	6% 4 2 5% 4 4 4 4 5% 7% 56%	2000
	11th to 20th	Day	8% 5% 2 5% 3 3 4 3 5% 7% 56%	2000
	21st to end	Day	10% 4 1 4 3 3 4 3 5% 7% 54%	2200
November	1st to 10th	Day	8% 5% 2 6% 4 5% 4 4 6% 7% 51%	2058
	11th to 20th	Day	10% 5% 2 6% 4 3 4 3 5% 5% 53%	2100
	21st to end	Day	13% 7% 2 5% 5% 4 4 4 6% 6% 45%	2100
December	1st to 10th	Day	17% 10% 3 6% 4 4 4 3 4 5% 40%	3360
	11th to 20th	Day	11% 7% 3 7% 5% 5% 5% 3 4 6% 44%	3833
	21st to end	Day	15% 7% 2 7% 4 4 4 3 5% 6% 43%	4587
January	1st to 10th	Night	21% 6% 2 5% 4 3 3 2 4 5% 44%	7634
	11th to 20th	Night	15% 6% 2 6% 3 3 3 3 4 5% 48%	7680
	21st to end	Night	22% 8% 3 7% 4 4 4 3 4 5% 35%	8250
February	1st to 10th	Night	16% 8% 3 6% 4 4 4 3 4 5% 43%	2520
	11th to 20th	Night	20% 8% 3 6% 3 3 3 3 5% 6% 40%	2458
	21st to end	Night	19% 8% 3 7% 3 4 3 3 5% 7% 39%	2076
March	1st to 10th	Night	19% 10% 3 7% 4 4 4 3 4 6% 38%	5037
	11th to 20th	Night	15% 7% 2 5% 3 4 3 3 4 5% 47%	5090
	21st to end	Night	16% 7% 3 6% 4 4 4 4 5% 5% 44%	5457
April	1st to 10th	Night	14% 6% 3 6% 4 4 4 3 6% 7% 44%	2100
	11th to 20th	Night	13% 6% 2 6% 4 3 3 3 5% 6% 48%	2075
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 7% 51%	2100
May	1st to 10th	Night	20% 8% 3 7% 4 4 4 3 5% 7% 35%	5832
	11th to 20th	Night	13% 7% 2 6% 4 4 4 3 5% 8% 41%	5829
	21st to end	Night	10% 7% 3 8% 5% 5% 5% 5% 7% 10% 35%	6415
June	1st to 10th	Night	6% 5% 2 6% 4 5% 5% 6% 8% 10% 43%	1951
	11th to 20th	Night	4 5% 2 5% 5% 5% 5% 4 7% 13% 44%	1890
	21st to end	Night	6% 4 2 6% 6% 5% 6% 6% 8% 12% 39%	1890
July	1st to 10th	Night	3 4 2 6% 5% 6% 7% 6% 9% 14% 38%	5308
	11th to 20th	Night	3 4 2 5% 5% 5% 6% 6% 10% 14% 40%	5307
	21st to end	Night	4 4 2 6% 5% 5% 6% 5% 9% 14% 38%	6050
August	1st to 10th	Night	2 3 1 3 3 3 4 4 6% 12% 59%	3344
	11th to 20th	Night	3 3 2 5% 5% 4 6% 5% 9% 14% 43%	3240
	21st to end	Night	6% 6% 3 8% 6% 5% 6% 5% 7% 9% 40%	3586
September	1st to 10th	Night	8% 4 3 7% 5% 5% 6% 4 7% 11% 42%	2000
	11th to 20th	Night	9% 6% 3 7% 6% 5% 4 5% 6% 8% 41%	2000
	21st to end	Night	7% 4 2 5% 5% 4 4 4 5% 7% 51%	2190
October	1st to 10th	Night	6% 4 2 4 4 4 4 3 5% 7% 58%	2400
	11th to 20th	Night	7% 4 2 5% 3 3 3 3 5% 5% 60%	2400
	21st to end	Night	11% 4 2 4 2 3 3 3 4 6% 57%	2640
November	1st to 10th	Night	9% 5% 2 5% 4 3 3 3 4 5% 57%	2460
	11th to 20th	Night	12% 5% 1 5% 3 3 3 3 5% 5% 56%	2520
	21st to end	Night	12% 8% 2 6% 3 3 3 3 5% 6% 48%	2520
December	1st to 10th	Night	19% 8% 3 7% 4 4 3 2 4 5% 42%	4040
	11th to 20th	Night	10% 9% 3 7% 4 4 4 3 5% 6% 45%	4576
	21st to end	Night	17% 9% 3 6% 4 3 3 2 3 5% 45%	6633

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	46% 4 6% 18% 22% 4	5290
	11th to 20th	Day	37% 3 5% 18% 27% 10%	5310
	21st to end	Day	52% 3 5% 12% 15% 12%	5940
February	1st to 10th	Day	47% 4 8% 14% 18% 10%	2100
	11th to 20th	Day	44% 5% 7% 15% 19% 9%	2058
	21st to end	Day	47% 4 7% 16% 18% 8%	1738
March	1st to 10th	Day	51% 4 8% 14% 13% 10%	5046
	11th to 20th	Day	39% 5% 8% 15% 17% 17%	5090
	21st to end	Day	43% 4 9% 18% 19% 7%	5714
April	1st to 10th	Day	41% 6% 10% 16% 18% 9%	2520
	11th to 20th	Day	41% 5% 9% 19% 16% 9%	2494
	21st to end	Day	37% 6% 12% 21% 21% 4	2520
May	1st to 10th	Day	50% 5% 12% 19% 11% 3	7056
	11th to 20th	Day	37% 6% 13% 23% 18% 3	7035
	21st to end	Day	41% 9% 16% 23% 9% 1	7749
June	1st to 10th	Day	42% 10% 13% 21% 13% 1	2662
	11th to 20th	Day	43% 11% 14% 19% 12% 1	2730
	21st to end	Day	44% 12% 17% 20% 6% 1	2730
July	1st to 10th	Day	40% 13% 28% 17% 3	7616
	11th to 20th	Day	42% 13% 32% 11% 2	7611
	21st to end	Day	41% 10% 20% 27% 2	7864
August	1st to 10th	Day	25% 7% 15% 29% 23% 1	4013
	11th to 20th	Day	35% 9% 22% 26% 7% 1	3933
	21st to end	Day	46% 9% 14% 15% 15% 2	4311
September	1st to 10th	Day	42% 10% 16% 16% 12% 3	2400
	11th to 20th	Day	41% 7% 14% 17% 16% 6%	2400
	21st to end	Day	35% 6% 11% 20% 18% 10%	2182
October	1st to 10th	Day	26% 4 7% 12% 22% 30%	3260
	11th to 20th	Day	18% 3 4 20% 27% 28%	3240
	21st to end	Day	24% 3 5% 12% 40% 17%	3538
November	1st to 10th	Day	31% 6% 8% 19% 25% 11%	2058
	11th to 20th	Day	33% 4 6% 17% 27% 13%	2100
	21st to end	Day	39% 4 8% 17% 23% 9%	2100
December	1st to 10th	Day	48% 3 7% 15% 21% 6%	3360
	11th to 20th	Day	41% 4 9% 15% 22% 10%	3831
	21st to end	Day	42% 4 6% 18% 24% 5%	4587
January	1st to 10th	Night	42% 3 8% 18% 22% 6%	7635
	11th to 20th	Night	39% 3 4 16% 25% 13%	7680
	21st to end	Night	51% 3 6% 12% 18% 9%	8250
February	1st to 10th	Night	43% 4 6% 16% 20% 11%	2520
	11th to 20th	Night	46% 4 5% 15% 18% 11%	2459
	21st to end	Night	45% 4 9% 14% 16% 11%	2076
March	1st to 10th	Night	48% 4 8% 12% 17% 11%	5037
	11th to 20th	Night	39% 4 8% 15% 18% 15%	5090
	21st to end	Night	42% 4 9% 20% 18% 7%	5457
April	1st to 10th	Night	38% 5% 12% 18% 16% 11%	2100
	11th to 20th	Night	37% 4 10% 21% 18% 11%	2075
	21st to end	Night	30% 6% 12% 22% 24% 6%	2100
May	1st to 10th	Night	49% 5% 12% 17% 14% 3	5862
	11th to 20th	Night	39% 6% 14% 23% 15% 3	5830
	21st to end	Night	41% 9% 19% 24% 7% 1	6427
June	1st to 10th	Night	33% 10% 19% 25% 13% 1	1951
	11th to 20th	Night	31% 9% 19% 27% 12% 2	1890
	21st to end	Night	34% 10% 24% 24% 8%	1890
July	1st to 10th	Night	31% 13% 38% 15% 3	5265
	11th to 20th	Night	30% 14% 41% 13% 2	5256
	21st to end	Night	33% 13% 23% 28% 3	5915
August	1st to 10th	Night	18% 8% 21% 30% 22% 1	3332
	11th to 20th	Night	27% 10% 28% 29% 5%	3270
	21st to end	Night	39% 9% 18% 17% 13% 3	3586
September	1st to 10th	Night	35% 10% 19% 20% 11% 5%	2000
	11th to 20th	Night	38% 8% 17% 17% 14% 6%	2000
	21st to end	Night	31% 6% 12% 23% 17% 11%	2190
October	1st to 10th	Night	25% 4 8% 15% 21% 28%	3920
	11th to 20th	Night	17% 3 5% 19% 29% 27%	3899
	21st to end	Night	20% 3 5% 13% 36% 23%	4252
November	1st to 10th	Night	31% 4 8% 20% 24% 13%	2460
	11th to 20th	Night	31% 3 8% 16% 26% 16%	2520
	21st to end	Night	37% 4 7% 19% 21% 12%	2520
December	1st to 10th	Night	47% 3 4 18% 23% 5%	4040
	11th to 20th	Night	39% 4 9% 17% 20% 11%	4577
	21st to end	Night	44% 3 7% 15% 23% 7%	6633

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	20% 17% 35% 19% 7% 2	330
	11th to 20th	Day	17% 17% 38% 20% 8% 1	330
	21st to end	Day	27% 14% 34% 20% 5%	363
February	1st to 10th	Day	21% 14% 32% 25% 8% 1	330
	11th to 20th	Day	26% 17% 32% 18% 7% 1	330
	21st to end	Day	17% 23% 40% 17% 4	273
March	1st to 10th	Day	22% 14% 35% 25% 4	330
	11th to 20th	Day	21% 19% 33% 20% 6% 2	330
	21st to end	Day	17% 13% 31% 26% 12% 1	415
April	1st to 10th	Day	17% 14% 30% 27% 11% 1	540
	11th to 20th	Day	17% 12% 31% 24% 14% 2	532
	21st to end	Day	12% 8% 27% 31% 18% 3	540
May	1st to 10th	Day	16% 7% 25% 29% 18% 4	543
	11th to 20th	Day	13% 5% 23% 27% 24% 9%	567
	21st to end	Day	7% 4 14% 31% 29% 15%	617
June	1st to 10th	Day	9% 3 13% 28% 29% 18%	712
	11th to 20th	Day	9% 3 10% 28% 35% 16%	780
	21st to end	Day	9% 3 9% 24% 30% 26%	780
July	1st to 10th	Day	8% 2 6% 21% 37% 27%	771
	11th to 20th	Day	8% 1 4 17% 37% 32%	768
	21st to end	Day	9% 2 6% 18% 37% 29%	744
August	1st to 10th	Day	5% 1 5% 16% 35% 39%	566
	11th to 20th	Day	8% 1 4 10% 33% 44%	535
	21st to end	Day	11% 2 6% 20% 35% 27%	583
September	1st to 10th	Day	10% 3 6% 19% 41% 22%	530
	11th to 20th	Day	9% 3 8% 21% 40% 20%	530
	21st to end	Day	11% 3 11% 25% 33% 17%	510
October	1st to 10th	Day	6% 4 18% 42% 21% 9%	330
	11th to 20th	Day	7% 5% 20% 34% 22% 12%	330
	21st to end	Day	16% 8% 21% 31% 19% 5%	363
November	1st to 10th	Day	14% 5% 24% 33% 19% 5%	330
	11th to 20th	Day	15% 8% 25% 31% 16% 5%	330
	21st to end	Day	15% 11% 33% 27% 11% 3	330
December	1st to 10th	Day	22% 10% 28% 25% 12% 3	330
	11th to 20th	Day	20% 12% 32% 27% 8% 1	330
	21st to end	Day	23% 12% 33% 19% 13% 1	363
January	1st to 10th	Night	22% 9% 31% 31% 7%	1050
	11th to 20th	Night	18% 11% 29% 33% 8%	1050
	21st to end	Night	22% 11% 32% 30% 6%	1107
February	1st to 10th	Night	20% 10% 31% 35% 4	840
	11th to 20th	Night	24% 11% 26% 31% 7%	823
	21st to end	Night	22% 13% 35% 27% 3	692
March	1st to 10th	Night	18% 9% 32% 33% 9%	638
	11th to 20th	Night	16% 8% 30% 34% 11%	630
	21st to end	Night	13% 8% 31% 35% 12%	693
April	1st to 10th	Night	17% 9% 30% 33% 11%	630
	11th to 20th	Night	17% 8% 30% 33% 11% 1	623
	21st to end	Night	9% 6% 29% 41% 14% 1	630
May	1st to 10th	Night	13% 5% 22% 43% 16% 1	630
	11th to 20th	Night	12% 4 20% 37% 25% 2	621
	21st to end	Night	8% 3 13% 39% 32% 6%	683
June	1st to 10th	Night	7% 3 7% 37% 40% 6%	630
	11th to 20th	Night	5% 2 6% 33% 46% 8%	630
	21st to end	Night	8% 1 5% 25% 45% 16%	630
July	1st to 10th	Night	6% 1 4 17% 52% 21%	615
	11th to 20th	Night	5% 1 3 13% 53% 24%	612
	21st to end	Night	5% 1 5% 19% 54% 17%	690
August	1st to 10th	Night	5% 3 15% 51% 25%	627
	11th to 20th	Night	5% 1 15% 50% 28%	606
	21st to end	Night	7% 1 5% 17% 47% 22%	660
September	1st to 10th	Night	8% 2 6% 23% 45% 16%	600
	11th to 20th	Night	12% 3 6% 23% 48% 9%	600
	21st to end	Night	9% 2 9% 30% 42% 8%	776
October	1st to 10th	Night	8% 2 14% 37% 35% 5%	800
	11th to 20th	Night	8% 4 17% 41% 28% 2	800
	21st to end	Night	13% 6% 18% 38% 22% 2	880
November	1st to 10th	Night	11% 4 19% 41% 22% 2	820
	11th to 20th	Night	13% 6% 23% 40% 17% 1	840
	21st to end	Night	16% 5% 29% 34% 15% 1	840
December	1st to 10th	Night	20% 8% 25% 32% 15%	840
	11th to 20th	Night	20% 8% 26% 37% 9%	844
	21st to end	Night	25% 8% 27% 30% 9% 1	1155

Page generated at 2026-08-12 02:37:17. Version ac07

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