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 2025-01-22.

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 8% 5% 4 4 3 5% 6% 30%	105146
	Night	20% 16% 5% 9% 5% 4 4 3 4 5% 26%	104208
Transparency	Day	53% 6% 13% 19% 9% 1	108752
	Night	59% 6% 10% 16% 8% 1	108690
Seeing	Day	28% 15% 28% 18% 8% 3	14723
	Night	29% 15% 25% 21% 9% 1	24276

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% 31% 10% 13% 6% 4 3 2 3 3 8%	2597
	11th to 20th	Day	14% 27% 10% 20% 7% 4 4 2 3 3 6%	2897
	21st to end	Day	22% 22% 9% 15% 6% 5% 5% 3 3 3 8%	3133
February	1st to 10th	Day	18% 22% 6% 15% 8% 5% 5% 3 3 3 12%	1710
	11th to 20th	Day	14% 20% 9% 15% 6% 5% 4 3 4 5% 16%	1663
	21st to end	Day	21% 16% 5% 12% 6% 5% 4 3 3 5% 20%	1493
March	1st to 10th	Day	21% 15% 4 8% 4 3 3 3 4 5% 29%	3432
	11th to 20th	Day	13% 22% 5% 7% 4 4 4 3 4 6% 28%	3480
	21st to end	Day	19% 13% 4 9% 5% 4 4 4 5% 6% 29%	3815
April	1st to 10th	Day	19% 15% 4 6% 4 3 4 3 4 6% 31%	2254
	11th to 20th	Day	20% 11% 3 7% 3 4 3 3 5% 7% 35%	2272
	21st to end	Day	22% 10% 3 6% 5% 4 4 3 4 5% 34%	2470
May	1st to 10th	Day	22% 9% 3 7% 4 5% 4 3 6% 7% 32%	4108
	11th to 20th	Day	18% 10% 3 8% 5% 5% 4 3 6% 7% 32%	4334
	21st to end	Day	14% 6% 2 6% 4 3 4 4 5% 8% 45%	4837
June	1st to 10th	Day	16% 8% 2 6% 4 4 4 4 5% 7% 39%	2660
	11th to 20th	Day	14% 6% 2 6% 4 5% 4 4 8% 9% 39%	2660
	21st to end	Day	15% 6% 2 5% 4 3 5% 4 6% 9% 42%	2660
July	1st to 10th	Day	10% 5% 2 5% 4 4 4 5% 7% 9% 44%	4440
	11th to 20th	Day	14% 6% 2 6% 4 4 4 4 6% 8% 43%	4421
	21st to end	Day	9% 6% 2 6% 4 5% 5% 5% 7% 8% 43%	4466
August	1st to 10th	Day	17% 6% 3 6% 4 4 4 4 6% 8% 39%	4104
	11th to 20th	Day	15% 6% 3 6% 5% 5% 5% 4 7% 9% 33%	4044
	21st to end	Day	14% 5% 2 6% 4 4 4 3 6% 9% 44%	4289
September	1st to 10th	Day	16% 6% 2 6% 4 4 4 4 6% 7% 40%	2280
	11th to 20th	Day	14% 4 2 5% 4 4 4 4 7% 8% 44%	2190
	21st to end	Day	18% 8% 3 7% 5% 5% 5% 4 5% 7% 33%	2036
October	1st to 10th	Day	22% 8% 3 8% 4 4 3 3 5% 7% 32%	1900
	11th to 20th	Day	25% 11% 3 7% 5% 4 5% 4 4 4 28%	1900
	21st to end	Day	29% 14% 3 8% 5% 4 4 2 4 5% 21%	2090
November	1st to 10th	Day	20% 14% 4 8% 5% 5% 4 3 5% 5% 27%	1765
	11th to 20th	Day	18% 24% 4 9% 3 4 3 2 5% 5% 22%	1600
	21st to end	Day	24% 25% 5% 8% 4 4 3 3 3 5% 15%	1600
December	1st to 10th	Day	24% 32% 11% 10% 4 3 3 2 2 3 7%	2600
	11th to 20th	Day	23% 23% 6% 17% 5% 3 3 3 3 4 11%	2986
	21st to end	Day	24% 25% 6% 12% 6% 4 3 2 3 4 11%	3960
January	1st to 10th	Night	20% 31% 9% 14% 5% 4 3 2 3 2 8%	4569
	11th to 20th	Night	14% 27% 9% 17% 9% 6% 3 2 3 3 7%	4279
	21st to end	Night	25% 25% 7% 14% 6% 4 3 2 3 2 8%	4546
February	1st to 10th	Night	20% 23% 6% 14% 6% 4 3 3 4 4 13%	2470
	11th to 20th	Night	17% 18% 7% 14% 8% 5% 4 3 4 5% 16%	2403
	21st to end	Night	20% 17% 5% 15% 6% 4 4 3 4 5% 17%	1956
March	1st to 10th	Night	23% 14% 4 8% 5% 4 3 2 3 4 29%	3408
	11th to 20th	Night	21% 21% 5% 8% 4 3 4 3 3 4 25%	3479
	21st to end	Night	17% 12% 4 8% 4 3 4 3 5% 5% 36%	3817
April	1st to 10th	Night	21% 16% 4 7% 4 3 3 2 5% 5% 30%	1925
	11th to 20th	Night	22% 10% 2 7% 5% 4 4 3 5% 6% 33%	1873
	21st to end	Night	20% 10% 3 6% 4 4 4 4 4 7% 34%	1710
May	1st to 10th	Night	27% 9% 3 7% 4 3 4 3 4 6% 30%	2833
	11th to 20th	Night	14% 8% 3 7% 6% 5% 4 5% 6% 8% 35%	2544
	21st to end	Night	15% 6% 2 5% 3 3 4 3 6% 8% 45%	2738
June	1st to 10th	Night	15% 7% 1 6% 6% 4 5% 5% 5% 8% 36%	1520
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 4 6% 7% 41%	1520
	21st to end	Night	17% 6% 2 6% 4 5% 6% 4 6% 7% 38%	1520
July	1st to 10th	Night	13% 7% 2 6% 4 3 4 4 5% 10% 42%	2520
	11th to 20th	Night	15% 6% 2 6% 4 4 4 3 5% 8% 42%	2536
	21st to end	Night	12% 5% 1 6% 5% 5% 4 5% 6% 7% 45%	3087
August	1st to 10th	Night	13% 8% 3 7% 4 4 4 4 6% 8% 39%	2825
	11th to 20th	Night	21% 8% 2 7% 4 4 4 3 6% 7% 34%	2785
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 7% 9% 41%	3334
September	1st to 10th	Night	17% 6% 3 6% 3 4 4 4 5% 7% 41%	1900
	11th to 20th	Night	15% 5% 2 5% 4 4 2 3 5% 6% 48%	1985
	21st to end	Night	21% 8% 2 6% 5% 3 4 4 7% 7% 33%	2143
October	1st to 10th	Night	20% 7% 2 7% 4 4 4 4 5% 6% 36%	2280
	11th to 20th	Night	27% 10% 4 8% 4 4 3 3 5% 5% 27%	2280
	21st to end	Night	32% 11% 3 7% 5% 3 4 3 5% 5% 24%	2508
November	1st to 10th	Night	21% 15% 3 7% 5% 4 3 3 4 5% 32%	2531
	11th to 20th	Night	19% 20% 5% 8% 5% 5% 4 3 4 5% 22%	2800
	21st to end	Night	22% 23% 5% 9% 5% 4 4 3 4 4 16%	2800
December	1st to 10th	Night	23% 30% 9% 11% 5% 4 4 3 3 3 7%	4580
	11th to 20th	Night	23% 27% 8% 13% 4 4 3 2 3 3 10%	5208
	21st to end	Night	25% 24% 6% 11% 5% 3 3 2 3 4 12%	6996

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	82% 6% 5% 6% 2	2598
	11th to 20th	Day	80% 8% 8% 4 1	2897
	21st to end	Day	83% 5% 8% 4 1	3133
February	1st to 10th	Day	78% 5% 8% 7% 2	1710
	11th to 20th	Day	72% 4 9% 11% 4	1672
	21st to end	Day	68% 4 10% 12% 5% 1	1493
March	1st to 10th	Day	57% 6% 11% 20% 6%	3435
	11th to 20th	Day	56% 5% 18% 15% 5% 1	3480
	21st to end	Day	56% 5% 10% 20% 8% 1	3815
April	1st to 10th	Day	55% 4 12% 18% 10%	2254
	11th to 20th	Day	49% 5% 13% 21% 11% 2	2272
	21st to end	Day	53% 4 11% 18% 13% 1	2470
May	1st to 10th	Day	50% 6% 13% 20% 9% 2	4120
	11th to 20th	Day	50% 8% 14% 20% 7% 1	4338
	21st to end	Day	37% 6% 14% 25% 14% 3	4837
June	1st to 10th	Day	43% 6% 14% 22% 14% 1	2660
	11th to 20th	Day	40% 7% 16% 24% 13%	2660
	21st to end	Day	39% 7% 16% 25% 13% 1	2660
July	1st to 10th	Day	36% 6% 14% 28% 15% 2	4370
	11th to 20th	Day	38% 6% 14% 25% 17%	4346
	21st to end	Day	37% 8% 17% 24% 14%	4324
August	1st to 10th	Day	43% 6% 15% 23% 12% 1	4091
	11th to 20th	Day	44% 8% 19% 22% 6%	4083
	21st to end	Day	37% 6% 14% 32% 11% 1	4289
September	1st to 10th	Day	42% 6% 14% 26% 11% 1	2280
	11th to 20th	Day	38% 6% 13% 29% 14% 1	2190
	21st to end	Day	50% 7% 12% 20% 10%	2036
October	1st to 10th	Day	44% 6% 14% 23% 12% 1	3160
	11th to 20th	Day	49% 5% 14% 19% 11% 1	3140
	21st to end	Day	52% 5% 14% 22% 7%	3428
November	1st to 10th	Day	59% 4 10% 16% 8% 2	1765
	11th to 20th	Day	65% 5% 10% 13% 5% 2	1600
	21st to end	Day	73% 4 9% 9% 4 1	1600
December	1st to 10th	Day	85% 4 5% 5% 1	2600
	11th to 20th	Day	78% 6% 8% 7% 1	2986
	21st to end	Day	78% 5% 9% 7% 2	3960
January	1st to 10th	Night	81% 6% 7% 4 2	4569
	11th to 20th	Night	80% 7% 7% 4 2	4279
	21st to end	Night	82% 5% 6% 5% 1	4546
February	1st to 10th	Night	76% 4 8% 9% 2	2470
	11th to 20th	Night	72% 4 9% 11% 4	2405
	21st to end	Night	69% 5% 8% 12% 5%	1956
March	1st to 10th	Night	59% 5% 10% 20% 5%	3418
	11th to 20th	Night	62% 5% 12% 14% 6% 1	3480
	21st to end	Night	50% 5% 12% 20% 12% 2	3817
April	1st to 10th	Night	58% 4 9% 19% 9% 1	1925
	11th to 20th	Night	51% 5% 11% 18% 12% 2	1873
	21st to end	Night	49% 5% 12% 19% 13% 2	1710
May	1st to 10th	Night	54% 6% 8% 19% 10% 3	2840
	11th to 20th	Night	44% 10% 16% 21% 7% 1	2545
	21st to end	Night	36% 7% 11% 25% 19% 3	2739
June	1st to 10th	Night	43% 8% 11% 22% 14% 1	1520
	11th to 20th	Night	41% 7% 13% 22% 17% 2	1520
	21st to end	Night	44% 7% 11% 23% 12% 2	1520
July	1st to 10th	Night	40% 5% 12% 24% 16% 3	2480
	11th to 20th	Night	39% 6% 13% 25% 15% 1	2488
	21st to end	Night	36% 7% 15% 23% 16% 2	2988
August	1st to 10th	Night	42% 6% 13% 28% 9% 1	2814
	11th to 20th	Night	48% 7% 16% 22% 7%	2812
	21st to end	Night	36% 6% 14% 30% 12% 1	3334
September	1st to 10th	Night	42% 7% 12% 24% 14% 2	1900
	11th to 20th	Night	36% 5% 14% 26% 17% 1	1985
	21st to end	Night	49% 7% 12% 20% 11% 1	2143
October	1st to 10th	Night	44% 7% 11% 21% 17% 1	3800
	11th to 20th	Night	53% 4 12% 18% 13% 1	3779
	21st to end	Night	48% 5% 15% 22% 10% 1	4120
November	1st to 10th	Night	56% 5% 8% 20% 10% 2	2531
	11th to 20th	Night	64% 5% 10% 13% 6% 2	2800
	21st to end	Night	72% 5% 10% 10% 3	2800
December	1st to 10th	Night	83% 6% 7% 4 1	4580
	11th to 20th	Night	81% 4 7% 7% 1	5208
	21st to end	Night	77% 5% 8% 8% 2	6996

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	37% 29% 24% 7% 4 1	200
	11th to 20th	Day	42% 30% 20% 6% 2 1	290
	21st to end	Day	36% 26% 26% 9% 3	300
February	1st to 10th	Day	43% 25% 25% 6% 1	270
	11th to 20th	Day	34% 33% 27% 4	270
	21st to end	Day	41% 25% 29% 5%	277
March	1st to 10th	Day	34% 20% 30% 12% 3 1	460
	11th to 20th	Day	34% 19% 32% 12% 3	460
	21st to end	Day	37% 20% 27% 12% 4 1	506
April	1st to 10th	Day	35% 20% 28% 12% 4	460
	11th to 20th	Day	35% 20% 23% 12% 7% 2	452
	21st to end	Day	34% 12% 33% 16% 4 1	460
May	1st to 10th	Day	33% 14% 29% 17% 5% 2	463
	11th to 20th	Day	24% 13% 29% 22% 9% 2	487
	21st to end	Day	18% 10% 33% 24% 11% 5%	529
June	1st to 10th	Day	22% 14% 34% 19% 9% 1	490
	11th to 20th	Day	19% 14% 26% 29% 11% 2	490
	21st to end	Day	22% 12% 33% 23% 8% 2	490
July	1st to 10th	Day	13% 8% 29% 28% 17% 4	485
	11th to 20th	Day	17% 10% 28% 26% 14% 4	484
	21st to end	Day	13% 9% 36% 27% 12% 4	532
August	1st to 10th	Day	15% 8% 26% 28% 16% 7%	486
	11th to 20th	Day	16% 8% 28% 25% 16% 6%	479
	21st to end	Day	17% 8% 28% 28% 13% 6%	539
September	1st to 10th	Day	19% 11% 25% 25% 13% 6%	490
	11th to 20th	Day	14% 8% 23% 27% 20% 9%	490
	21st to end	Day	23% 17% 25% 19% 12% 4	490
October	1st to 10th	Day	24% 14% 26% 19% 14% 4	490
	11th to 20th	Day	34% 17% 26% 16% 6% 1	490
	21st to end	Day	42% 16% 24% 16% 3	539
November	1st to 10th	Day	32% 18% 28% 15% 6% 1	355
	11th to 20th	Day	44% 19% 26% 10% 1 1	200
	21st to end	Day	49% 22% 22% 7% 1	200
December	1st to 10th	Day	48% 18% 24% 7% 4 1	200
	11th to 20th	Day	45% 21% 25% 9% 1	200
	21st to end	Day	43% 20% 29% 6% 2	220
January	1st to 10th	Night	39% 25% 23% 10% 3	800
	11th to 20th	Night	38% 24% 24% 11% 2	800
	21st to end	Night	31% 23% 28% 14% 3	841
February	1st to 10th	Night	37% 23% 23% 15% 1	760
	11th to 20th	Night	32% 24% 30% 12% 2	743
	21st to end	Night	35% 23% 26% 15% 1	628
March	1st to 10th	Night	30% 19% 30% 17% 4	760
	11th to 20th	Night	34% 17% 28% 16% 4	760
	21st to end	Night	28% 15% 32% 17% 6% 1	836
April	1st to 10th	Night	31% 16% 28% 21% 4	760
	11th to 20th	Night	31% 13% 27% 21% 7% 1	749
	21st to end	Night	26% 9% 31% 27% 6% 1	570
May	1st to 10th	Night	27% 9% 22% 30% 10% 1	570
	11th to 20th	Night	15% 8% 28% 40% 7% 1	410
	21st to end	Night	15% 11% 24% 31% 17% 2	411
June	1st to 10th	Night	18% 8% 30% 30% 13% 1	380
	11th to 20th	Night	16% 9% 24% 39% 11% 1	380
	21st to end	Night	19% 8% 29% 32% 12% 1	380
July	1st to 10th	Night	11% 5% 20% 42% 19% 2	370
	11th to 20th	Night	15% 5% 23% 35% 20% 1	371
	21st to end	Night	15% 4 24% 36% 19% 2	624
August	1st to 10th	Night	13% 4 19% 40% 22% 2	567
	11th to 20th	Night	15% 5% 19% 33% 27% 2	564
	21st to end	Night	15% 7% 21% 32% 23% 3	746
September	1st to 10th	Night	20% 9% 20% 29% 18% 4	760
	11th to 20th	Night	16% 7% 19% 28% 28% 3	760
	21st to end	Night	24% 11% 22% 25% 14% 4	760
October	1st to 10th	Night	23% 12% 24% 23% 16% 2	760
	11th to 20th	Night	34% 16% 24% 20% 6% 1	760
	21st to end	Night	38% 16% 25% 18% 3	836
November	1st to 10th	Night	32% 15% 27% 18% 6% 1	780
	11th to 20th	Night	36% 19% 26% 13% 5% 1	800
	21st to end	Night	41% 19% 25% 11% 4	800
December	1st to 10th	Night	45% 22% 20% 10% 3	800
	11th to 20th	Night	40% 25% 23% 11% 2	800
	21st to end	Night	41% 22% 24% 12% 2	880

Page generated at 2025-01-19 03:06:43. Version ac07

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