Kitters Angola Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kitters Angola Observatory clear sky chart from 2005-11-06 to 2026-05-17.

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	18% 13% 4 9% 5% 4 4 3 5% 6% 29%	132135
	Night	19% 16% 5% 11% 5% 4 4 3 4 5% 25%	130638
Transparency	Day	55% 5% 12% 18% 9% 1	135730
	Night	60% 5% 10% 15% 8% 1	135129
Seeing	Day	29% 16% 27% 18% 8% 2	16429
	Night	29% 15% 25% 21% 9% 1	25970

By Month

Percentage Cloud Cover NE (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% 27% 10% 18% 5% 3 2 2 3 3 7%	4661
	11th to 20th	Day	12% 26% 12% 21% 11% 4 3 2 2 3 4	5186
	21st to end	Day	16% 18% 8% 18% 9% 8% 5% 3 4 3 9%	5780
February	1st to 10th	Day	17% 21% 7% 15% 8% 5% 5% 3 3 3 13%	1890
	11th to 20th	Day	15% 20% 8% 15% 6% 4 4 3 4 4 16%	1843
	21st to end	Day	21% 16% 5% 11% 6% 5% 4 3 3 5% 19%	1646
March	1st to 10th	Day	17% 16% 6% 11% 5% 3 3 3 4 5% 27%	5042
	11th to 20th	Day	13% 19% 5% 7% 4 3 4 3 4 6% 31%	5090
	21st to end	Day	22% 14% 4 8% 4 4 3 3 4 5% 28%	5586
April	1st to 10th	Day	20% 15% 4 7% 4 3 4 3 5% 5% 30%	2492
	11th to 20th	Day	20% 12% 3 7% 3 4 3 3 5% 6% 34%	2514
	21st to end	Day	22% 10% 3 6% 4 4 4 3 4 5% 35%	2730
May	1st to 10th	Day	25% 9% 3 7% 4 5% 4 3 5% 6% 29%	6018
	11th to 20th	Day	19% 9% 3 8% 4 4 4 3 5% 7% 32%	6308
	21st to end	Day	23% 7% 2 6% 4 3 4 3 4 7% 37%	6949
June	1st to 10th	Day	15% 8% 2 6% 4 4 4 4 6% 7% 39%	2800
	11th to 20th	Day	14% 6% 2 7% 4 5% 4 4 8% 8% 38%	2800
	21st to end	Day	15% 6% 2 5% 3 3 5% 4 6% 9% 42%	2800
July	1st to 10th	Day	10% 5% 2 6% 4 4 4 4 6% 9% 44%	6360
	11th to 20th	Day	14% 7% 2 7% 4 4 4 4 6% 8% 41%	6327
	21st to end	Day	11% 5% 2 6% 4 4 4 4 6% 7% 47%	6424
August	1st to 10th	Day	17% 5% 3 6% 4 4 4 4 6% 8% 40%	4234
	11th to 20th	Day	16% 6% 3 6% 5% 5% 5% 4 7% 9% 34%	4174
	21st to end	Day	13% 5% 2 6% 4 4 4 3 6% 9% 44%	4424
September	1st to 10th	Day	16% 6% 2 6% 4 4 4 4 6% 7% 42%	2400
	11th to 20th	Day	14% 4 2 5% 4 4 4 4 7% 8% 45%	2305
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 4 5% 7% 33%	2143
October	1st to 10th	Day	22% 8% 3 8% 4 4 3 2 5% 7% 35%	2000
	11th to 20th	Day	24% 11% 3 7% 5% 4 5% 4 4 5% 29%	2000
	21st to end	Day	29% 14% 3 8% 5% 5% 4 2 4 5% 22%	2200
November	1st to 10th	Day	20% 14% 4 8% 5% 5% 4 3 4 6% 27%	1855
	11th to 20th	Day	18% 24% 4 9% 3 4 3 2 5% 5% 22%	1680
	21st to end	Day	24% 26% 5% 8% 4 4 3 3 3 5% 15%	1680
December	1st to 10th	Day	23% 32% 11% 10% 4 3 3 2 2 3 7%	2680
	11th to 20th	Day	23% 23% 6% 17% 5% 4 3 3 3 4 11%	3066
	21st to end	Day	24% 24% 6% 12% 5% 4 3 2 3 4 11%	4048
January	1st to 10th	Night	18% 28% 9% 22% 5% 3 2 2 3 2 6%	8234
	11th to 20th	Night	13% 26% 11% 22% 9% 5% 3 2 2 2 4	7682
	21st to end	Night	17% 19% 7% 17% 10% 7% 5% 2 3 3 9%	8401
February	1st to 10th	Night	19% 22% 6% 15% 7% 4 3 3 3 4 14%	2730
	11th to 20th	Night	17% 19% 7% 14% 7% 5% 4 3 4 5% 16%	2663
	21st to end	Night	19% 18% 6% 15% 6% 4 4 3 4 5% 16%	2154
March	1st to 10th	Night	20% 15% 5% 9% 6% 4 4 3 4 4 26%	5018
	11th to 20th	Night	17% 17% 4 7% 3 4 4 3 4 5% 32%	5089
	21st to end	Night	18% 15% 5% 9% 4 3 3 3 4 5% 31%	5588
April	1st to 10th	Night	21% 16% 4 8% 5% 3 3 2 5% 4 28%	2127
	11th to 20th	Night	22% 10% 2 7% 5% 4 4 3 5% 7% 32%	2073
	21st to end	Night	20% 9% 2 6% 4 4 4 4 5% 6% 35%	1890
May	1st to 10th	Night	27% 10% 4 7% 4 4 4 3 4 5% 28%	4143
	11th to 20th	Night	16% 8% 3 7% 5% 4 4 4 6% 7% 36%	3702
	21st to end	Night	22% 8% 3 6% 3 3 3 3 5% 7% 37%	3926
June	1st to 10th	Night	15% 7% 2 6% 6% 4 5% 5% 5% 8% 36%	1600
	11th to 20th	Night	13% 8% 2 6% 5% 4 5% 4 6% 7% 41%	1600
	21st to end	Night	16% 6% 2 6% 4 5% 6% 4 6% 7% 39%	1600
July	1st to 10th	Night	14% 6% 2 6% 4 3 5% 3 6% 10% 41%	3600
	11th to 20th	Night	14% 6% 2 6% 4 4 5% 3 6% 8% 41%	3616
	21st to end	Night	11% 5% 2 6% 4 4 4 4 6% 7% 47%	4428
August	1st to 10th	Night	13% 8% 3 7% 4 4 4 3 6% 8% 39%	2915
	11th to 20th	Night	20% 8% 2 7% 4 4 4 3 6% 7% 34%	2875
	21st to end	Night	12% 6% 2 5% 4 4 5% 4 7% 9% 41%	3440
September	1st to 10th	Night	16% 6% 3 6% 3 4 4 4 5% 7% 41%	2000
	11th to 20th	Night	14% 5% 2 5% 4 4 3 3 5% 6% 50%	2090
	21st to end	Night	20% 9% 2 6% 5% 3 4 4 6% 7% 33%	2256
October	1st to 10th	Night	19% 7% 2 7% 4 4 4 4 5% 6% 38%	2400
	11th to 20th	Night	26% 10% 4 8% 4 4 3 3 5% 5% 28%	2400
	21st to end	Night	31% 11% 3 7% 5% 3 4 3 4 5% 24%	2640
November	1st to 10th	Night	21% 15% 3 7% 5% 4 3 3 4 4 31%	2660
	11th to 20th	Night	19% 20% 5% 8% 5% 5% 4 3 4 5% 22%	2940
	21st to end	Night	22% 23% 5% 9% 5% 4 4 3 4 4 16%	2940
December	1st to 10th	Night	23% 30% 9% 11% 5% 4 4 3 3 3 7%	4720
	11th to 20th	Night	23% 26% 8% 14% 4 4 3 3 3 3 10%	5348
	21st to end	Night	25% 24% 6% 12% 5% 3 3 3 3 4 12%	7150

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	83% 5% 5% 5% 2	4662
	11th to 20th	Day	85% 5% 6% 2 2	5220
	21st to end	Day	81% 4 8% 5% 1	5780
February	1st to 10th	Day	78% 5% 7% 8% 2	1890
	11th to 20th	Day	73% 4 9% 10% 3	1852
	21st to end	Day	69% 5% 9% 12% 4 1	1646
March	1st to 10th	Day	60% 5% 13% 16% 6%	5045
	11th to 20th	Day	54% 5% 18% 16% 6% 1	5090
	21st to end	Day	59% 4 8% 19% 9% 1	5586
April	1st to 10th	Day	57% 4 12% 17% 10%	2492
	11th to 20th	Day	50% 5% 12% 20% 11% 2	2514
	21st to end	Day	52% 4 11% 19% 12% 1	2730
May	1st to 10th	Day	54% 6% 11% 17% 8% 4	6027
	11th to 20th	Day	51% 7% 11% 21% 10% 1	6312
	21st to end	Day	48% 5% 13% 21% 11% 2	6949
June	1st to 10th	Day	43% 6% 14% 22% 14% 1	2800
	11th to 20th	Day	42% 7% 15% 23% 12%	2800
	21st to end	Day	38% 7% 16% 24% 13% 1	2800
July	1st to 10th	Day	36% 6% 14% 27% 16% 1	6290
	11th to 20th	Day	40% 6% 14% 23% 17%	6252
	21st to end	Day	35% 7% 15% 26% 17%	6240
August	1st to 10th	Day	42% 6% 15% 23% 13% 1	4221
	11th to 20th	Day	44% 8% 18% 22% 7%	4213
	21st to end	Day	37% 6% 14% 33% 11% 1	4424
September	1st to 10th	Day	41% 6% 14% 27% 11% 1	2400
	11th to 20th	Day	37% 6% 12% 30% 14% 1	2305
	21st to end	Day	50% 7% 13% 20% 10% 1	2143
October	1st to 10th	Day	43% 6% 14% 24% 13% 1	3260
	11th to 20th	Day	50% 5% 14% 18% 11% 1	3240
	21st to end	Day	52% 5% 14% 21% 7% 1	3538
November	1st to 10th	Day	59% 4 10% 17% 8% 2	1855
	11th to 20th	Day	65% 5% 9% 13% 5% 2	1680
	21st to end	Day	74% 4 9% 9% 4 1	1680
December	1st to 10th	Day	85% 4 5% 6% 1	2680
	11th to 20th	Day	78% 6% 8% 7% 1	3066
	21st to end	Day	78% 5% 9% 6% 2	4048
January	1st to 10th	Night	85% 5% 5% 3 2	8234
	11th to 20th	Night	85% 5% 6% 3 1	7723
	21st to end	Night	78% 4 9% 6% 2	8401
February	1st to 10th	Night	76% 4 8% 10% 2	2730
	11th to 20th	Night	72% 4 10% 11% 3	2665
	21st to end	Night	71% 5% 8% 11% 5%	2154
March	1st to 10th	Night	61% 5% 10% 16% 6% 1	5028
	11th to 20th	Night	53% 5% 14% 19% 8% 2	5090
	21st to end	Night	55% 5% 10% 17% 12% 1	5588
April	1st to 10th	Night	60% 4 9% 18% 9% 1	2127
	11th to 20th	Night	52% 5% 11% 18% 12% 2	2073
	21st to end	Night	49% 5% 11% 20% 13% 2	1890
May	1st to 10th	Night	58% 5% 7% 15% 10% 5%	4150
	11th to 20th	Night	45% 9% 14% 21% 10% 1	3703
	21st to end	Night	45% 6% 11% 22% 13% 2	3927
June	1st to 10th	Night	43% 8% 11% 22% 14% 2	1600
	11th to 20th	Night	41% 7% 13% 21% 16% 2	1600
	21st to end	Night	44% 7% 12% 23% 13% 2	1600
July	1st to 10th	Night	40% 5% 12% 26% 15% 2	3560
	11th to 20th	Night	40% 7% 11% 24% 16% 1	3568
	21st to end	Night	35% 6% 13% 23% 21% 2	4297
August	1st to 10th	Night	42% 6% 13% 28% 10% 2	2904
	11th to 20th	Night	48% 6% 16% 22% 7%	2902
	21st to end	Night	37% 6% 14% 30% 11% 1	3440
September	1st to 10th	Night	41% 7% 12% 25% 14% 2	2000
	11th to 20th	Night	35% 5% 14% 28% 17% 1	2090
	21st to end	Night	49% 7% 12% 20% 11% 1	2256
October	1st to 10th	Night	43% 7% 10% 22% 17% 1	3920
	11th to 20th	Night	52% 4 12% 18% 13% 1	3899
	21st to end	Night	48% 5% 15% 21% 11% 1	4252
November	1st to 10th	Night	56% 5% 8% 19% 9% 2	2660
	11th to 20th	Night	64% 5% 10% 13% 5% 2	2940
	21st to end	Night	72% 5% 10% 10% 3	2940
December	1st to 10th	Night	83% 6% 7% 4 1	4720
	11th to 20th	Night	80% 4 7% 7% 1	5348
	21st to end	Night	77% 5% 8% 8% 2	7150

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	38% 29% 23% 6% 4 1	220
	11th to 20th	Day	44% 29% 19% 5% 2 1	319
	21st to end	Day	39% 26% 25% 9% 2	363
February	1st to 10th	Day	42% 23% 25% 8% 1	330
	11th to 20th	Day	37% 31% 28% 4	330
	21st to end	Day	42% 24% 30% 5%	331
March	1st to 10th	Day	35% 20% 29% 11% 4 1	540
	11th to 20th	Day	37% 20% 29% 11% 2	540
	21st to end	Day	37% 20% 27% 11% 4 1	594
April	1st to 10th	Day	37% 20% 27% 12% 4	540
	11th to 20th	Day	36% 21% 23% 12% 6% 2	532
	21st to end	Day	34% 13% 33% 16% 4 1	540
May	1st to 10th	Day	33% 17% 29% 15% 5% 2	543
	11th to 20th	Day	25% 14% 29% 21% 9% 2	551
	21st to end	Day	22% 10% 32% 22% 10% 4	573
June	1st to 10th	Day	22% 15% 34% 18% 9% 1	530
	11th to 20th	Day	20% 15% 26% 27% 10% 2	530
	21st to end	Day	21% 12% 34% 22% 8% 2	530
July	1st to 10th	Day	12% 9% 29% 29% 16% 4	525
	11th to 20th	Day	17% 10% 29% 27% 14% 4	524
	21st to end	Day	13% 8% 35% 28% 12% 4	576
August	1st to 10th	Day	14% 8% 25% 29% 17% 6%	526
	11th to 20th	Day	17% 8% 27% 26% 16% 6%	519
	21st to end	Day	17% 9% 28% 28% 13% 5%	583
September	1st to 10th	Day	19% 12% 24% 26% 14% 6%	530
	11th to 20th	Day	13% 7% 22% 28% 20% 9%	530
	21st to end	Day	22% 17% 24% 20% 12% 4	530
October	1st to 10th	Day	22% 13% 26% 20% 15% 4	530
	11th to 20th	Day	34% 17% 27% 15% 5% 1	530
	21st to end	Day	42% 15% 24% 16% 3	583
November	1st to 10th	Day	34% 19% 26% 15% 5% 1	385
	11th to 20th	Day	46% 17% 24% 10% 1 1	220
	21st to end	Day	50% 21% 22% 6%	220
December	1st to 10th	Day	48% 17% 24% 7% 3	220
	11th to 20th	Day	47% 20% 24% 8%	220
	21st to end	Day	44% 20% 28% 6% 2	242
January	1st to 10th	Night	39% 25% 23% 10% 3	840
	11th to 20th	Night	40% 24% 23% 11% 2	840
	21st to end	Night	31% 24% 28% 14% 3	924
February	1st to 10th	Night	36% 22% 24% 16% 2	840
	11th to 20th	Night	33% 23% 30% 12% 2	823
	21st to end	Night	35% 23% 27% 15% 1	692
March	1st to 10th	Night	31% 19% 30% 16% 4	840
	11th to 20th	Night	35% 17% 27% 16% 4	840
	21st to end	Night	30% 15% 32% 17% 6% 1	924
April	1st to 10th	Night	32% 16% 28% 20% 4	840
	11th to 20th	Night	32% 13% 26% 20% 7% 1	829
	21st to end	Night	26% 10% 30% 28% 5% 1	630
May	1st to 10th	Night	27% 9% 24% 29% 10% 1	630
	11th to 20th	Night	16% 8% 29% 39% 7% 1	446
	21st to end	Night	17% 11% 24% 30% 16% 2	433
June	1st to 10th	Night	17% 8% 31% 30% 13% 1	400
	11th to 20th	Night	17% 10% 24% 38% 11% 1	400
	21st to end	Night	18% 8% 28% 33% 13% 1	400
July	1st to 10th	Night	12% 5% 20% 42% 19% 2	390
	11th to 20th	Night	15% 5% 23% 35% 20% 1	391
	21st to end	Night	15% 4 23% 37% 19% 2	657
August	1st to 10th	Night	13% 4 19% 41% 21% 2	597
	11th to 20th	Night	15% 5% 19% 34% 27% 2	594
	21st to end	Night	15% 7% 21% 32% 22% 2	786
September	1st to 10th	Night	19% 10% 21% 30% 18% 4	800
	11th to 20th	Night	15% 7% 18% 29% 29% 3	800
	21st to end	Night	24% 11% 22% 26% 14% 4	800
October	1st to 10th	Night	23% 12% 24% 24% 16% 2	800
	11th to 20th	Night	33% 15% 25% 20% 6% 1	800
	21st to end	Night	38% 16% 25% 18% 3	880
November	1st to 10th	Night	33% 15% 27% 18% 6% 1	820
	11th to 20th	Night	37% 19% 26% 12% 5% 1	840
	21st to end	Night	42% 20% 24% 10% 4	840
December	1st to 10th	Night	44% 22% 20% 10% 3	840
	11th to 20th	Night	40% 25% 23% 10% 2	840
	21st to end	Night	41% 22% 24% 11% 2	924

Page generated at 2026-05-14 01:59:00. Version ac07

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