Kennett
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kennett clear sky chart from 2005-11-06 to 2026-04-02.

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	12% 6% 2 6% 4 4 4 4 5% 8% 45%	131098
	Night	13% 6% 2 6% 4 4 4 3 5% 7% 48%	130925
Transparency	Day	37% 5% 11% 25% 18% 4	134720
	Night	35% 4 10% 25% 20% 5%	135381
Seeing	Day	14% 7% 22% 26% 21% 10%	17244
	Night	15% 6% 26% 33% 18% 2	27160

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% 2 9% 4 4 3 3 5% 6% 41%	4769
	11th to 20th	Day	12% 6% 2 6% 3 3 3 2 3 5% 54%	5310
	21st to end	Day	19% 7% 2 5% 3 3 3 2 4 5% 45%	5812
February	1st to 10th	Day	18% 9% 3 6% 4 3 4 3 5% 6% 39%	1983
	11th to 20th	Day	19% 9% 3 6% 4 3 4 3 5% 6% 38%	2048
	21st to end	Day	19% 9% 4 6% 4 4 4 3 6% 5% 37%	1730
March	1st to 10th	Day	17% 10% 3 7% 4 4 4 3 4 5% 37%	4622
	11th to 20th	Day	12% 5% 2 4 4 3 3 3 5% 6% 52%	5090
	21st to end	Day	12% 6% 3 7% 5% 5% 5% 3 5% 7% 41%	5911
April	1st to 10th	Day	13% 6% 2 6% 4 3 3 3 5% 7% 48%	2412
	11th to 20th	Day	15% 7% 2 6% 4 3 4 4 5% 6% 43%	2374
	21st to end	Day	16% 7% 3 5% 5% 4 4 4 5% 7% 40%	2400
May	1st to 10th	Day	13% 8% 3 7% 5% 5% 6% 4 7% 10% 31%	5405
	11th to 20th	Day	14% 7% 2 8% 5% 5% 5% 5% 7% 10% 32%	5832
	21st to end	Day	17% 6% 2 6% 4 4 4 4 6% 8% 38%	6935
June	1st to 10th	Day	8% 5% 1 6% 5% 5% 4 5% 7% 10% 46%	2800
	11th to 20th	Day	5% 4 1 5% 4 5% 5% 5% 7% 11% 48%	2800
	21st to end	Day	4 3 1 5% 5% 4 5% 5% 8% 10% 50%	2800
July	1st to 10th	Day	7% 4 2 6% 4 5% 5% 4 7% 9% 46%	6360
	11th to 20th	Day	5% 3 1 4 4 4 4 4 7% 12% 53%	6251
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 6% 11% 42%	6422
August	1st to 10th	Day	4 2 1 3 3 3 4 3 6% 10% 62%	4018
	11th to 20th	Day	9% 5% 2 6% 3 4 5% 4 5% 8% 49%	3849
	21st to end	Day	5% 3 2 4 3 4 3 3 6% 7% 60%	4312
September	1st to 10th	Day	10% 5% 2 5% 4 5% 4 4 6% 8% 48%	2400
	11th to 20th	Day	13% 5% 2 5% 3 4 3 4 6% 8% 47%	2349
	21st to end	Day	11% 5% 2 5% 3 3 4 3 5% 7% 53%	2200
October	1st to 10th	Day	7% 4 1 5% 4 3 3 3 3 7% 61%	2051
	11th to 20th	Day	12% 5% 2 4 3 3 3 3 4 6% 55%	2000
	21st to end	Day	19% 6% 2 4 2 3 3 3 4 5% 50%	2200
November	1st to 10th	Day	11% 6% 2 5% 3 2 3 2 4 6% 55%	1877
	11th to 20th	Day	13% 7% 2 5% 4 3 3 3 3 5% 52%	1890
	21st to end	Day	19% 7% 2 5% 3 3 3 3 4 6% 44%	1890
December	1st to 10th	Day	14% 7% 3 6% 3 3 4 3 5% 5% 48%	2838
	11th to 20th	Day	17% 7% 3 6% 3 3 3 3 4 6% 43%	3088
	21st to end	Day	19% 10% 4 8% 5% 4 4 4 4 6% 32%	4070
January	1st to 10th	Night	17% 6% 2 6% 3 3 4 3 5% 6% 44%	8138
	11th to 20th	Night	11% 6% 2 5% 3 3 3 2 4 5% 56%	7680
	21st to end	Night	20% 7% 3 6% 4 3 3 3 4 5% 43%	8402
February	1st to 10th	Night	19% 8% 3 6% 4 3 3 3 4 5% 42%	2635
	11th to 20th	Night	19% 6% 2 6% 4 3 3 3 5% 5% 43%	2458
	21st to end	Night	17% 7% 2 6% 4 4 3 3 5% 5% 44%	2076
March	1st to 10th	Night	17% 8% 2 7% 4 4 4 3 5% 5% 42%	5493
	11th to 20th	Night	11% 6% 2 5% 4 4 4 3 5% 6% 50%	5090
	21st to end	Night	12% 5% 2 7% 5% 4 4 3 5% 8% 45%	5246
April	1st to 10th	Night	12% 5% 2 5% 4 3 4 4 5% 6% 49%	2010
	11th to 20th	Night	14% 4 2 6% 3 4 3 3 5% 7% 48%	1975
	21st to end	Night	14% 6% 2 6% 4 4 5% 2 4 9% 43%	2000
May	1st to 10th	Night	18% 8% 3 6% 4 4 5% 3 5% 7% 37%	4490
	11th to 20th	Night	16% 8% 3 8% 4 4 4 3 5% 7% 37%	4044
	21st to end	Night	16% 6% 2 7% 4 5% 4 4 6% 8% 37%	3942
June	1st to 10th	Night	8% 5% 2 4 4 5% 4 5% 6% 8% 49%	1600
	11th to 20th	Night	4 4 1 4 4 3 3 3 6% 10% 58%	1600
	21st to end	Night	3 4 1 4 4 3 3 5% 7% 11% 56%	1600
July	1st to 10th	Night	7% 4 2 5% 4 6% 5% 4 7% 9% 47%	3618
	11th to 20th	Night	4 4 1 4 4 3 5% 4 7% 10% 54%	3708
	21st to end	Night	7% 6% 3 7% 4 4 5% 4 5% 9% 46%	4449
August	1st to 10th	Night	3 2 1 3 3 3 4 3 6% 8% 64%	3131
	11th to 20th	Night	6% 3 2 4 3 4 4 4 6% 9% 53%	3200
	21st to end	Night	4 3 1 4 3 4 3 3 6% 10% 58%	3586
September	1st to 10th	Night	9% 5% 1 4 3 3 4 3 5% 7% 57%	2000
	11th to 20th	Night	9% 4 2 5% 4 4 4 3 6% 7% 53%	2030
	21st to end	Night	9% 6% 2 4 4 3 3 3 5% 6% 57%	2200
October	1st to 10th	Night	7% 4 1 4 3 2 3 3 5% 6% 62%	2345
	11th to 20th	Night	13% 4 2 4 3 3 3 2 3 5% 58%	2400
	21st to end	Night	17% 5% 1 5% 3 3 4 2 4 5% 51%	2640
November	1st to 10th	Night	13% 4 2 5% 3 2 2 2 4 5% 57%	2640
	11th to 20th	Night	12% 4 2 4 3 3 3 3 5% 6% 55%	2730
	21st to end	Night	17% 4 2 5% 4 3 4 3 4 6% 50%	2730
December	1st to 10th	Night	16% 6% 2 5% 3 2 3 2 4 6% 51%	4550
	11th to 20th	Night	18% 7% 2 5% 4 3 3 2 4 5% 46%	5339
	21st to end	Night	22% 8% 3 6% 4 4 4 3 4 5% 37%	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	45% 2 12% 26% 13% 1	4770
	11th to 20th	Day	35% 3 6% 33% 22% 2	5310
	21st to end	Day	42% 3 9% 21% 20% 6%	5812
February	1st to 10th	Day	47% 5% 11% 23% 14% 1	1983
	11th to 20th	Day	48% 5% 9% 20% 14% 3	2058
	21st to end	Day	48% 5% 9% 18% 14% 5%	1730
March	1st to 10th	Day	49% 4 7% 18% 14% 8%	4622
	11th to 20th	Day	33% 4 7% 28% 20% 8%	5090
	21st to end	Day	42% 4 10% 27% 16%	5913
April	1st to 10th	Day	37% 5% 11% 25% 20% 2	2412
	11th to 20th	Day	41% 5% 9% 22% 18% 5%	2374
	21st to end	Day	42% 5% 10% 24% 18% 1	2400
May	1st to 10th	Day	46% 7% 15% 19% 11% 1	5440
	11th to 20th	Day	46% 8% 15% 19% 12% 1	5836
	21st to end	Day	42% 7% 10% 23% 16% 2	6949
June	1st to 10th	Day	32% 7% 14% 24% 21% 2	2800
	11th to 20th	Day	28% 7% 13% 30% 19% 4	2800
	21st to end	Day	26% 8% 14% 26% 21% 5%	2800
July	1st to 10th	Day	33% 7% 13% 25% 20% 2	6291
	11th to 20th	Day	24% 8% 18% 36% 13% 2	6176
	21st to end	Day	36% 8% 17% 33% 7%	6240
August	1st to 10th	Day	18% 7% 16% 32% 24% 2	4004
	11th to 20th	Day	33% 6% 16% 25% 17% 2	3885
	21st to end	Day	23% 6% 11% 35% 22% 3	4311
September	1st to 10th	Day	31% 7% 11% 27% 19% 4	2400
	11th to 20th	Day	34% 5% 9% 25% 23% 3	2349
	21st to end	Day	32% 6% 8% 21% 27% 6%	2200
October	1st to 10th	Day	16% 3 6% 16% 44% 15%	3337
	11th to 20th	Day	21% 3 6% 22% 35% 13%	3240
	21st to end	Day	30% 3 5% 28% 29% 5%	3538
November	1st to 10th	Day	31% 4 9% 27% 23% 7%	1877
	11th to 20th	Day	36% 3 7% 24% 24% 5%	1890
	21st to end	Day	43% 4 7% 22% 21% 3	1890
December	1st to 10th	Day	40% 3 8% 30% 17% 2	2838
	11th to 20th	Day	44% 3 10% 25% 15% 3	3085
	21st to end	Day	53% 4 9% 22% 10% 2	4070
January	1st to 10th	Night	42% 4 10% 29% 14% 2	8139
	11th to 20th	Night	33% 3 7% 22% 30% 5%	7680
	21st to end	Night	45% 3 9% 20% 19% 3	8402
February	1st to 10th	Night	45% 3 9% 23% 18% 2	2635
	11th to 20th	Night	43% 5% 9% 23% 17% 4	2459
	21st to end	Night	42% 4 8% 21% 19% 6%	2076
March	1st to 10th	Night	44% 4 7% 16% 19% 10%	5493
	11th to 20th	Night	35% 5% 8% 23% 17% 13%	5090
	21st to end	Night	37% 5% 9% 28% 18% 2	5246
April	1st to 10th	Night	35% 4 10% 25% 20% 5%	2010
	11th to 20th	Night	35% 5% 8% 24% 21% 8%	1975
	21st to end	Night	39% 5% 9% 26% 18% 3	2000
May	1st to 10th	Night	47% 6% 14% 23% 10% 1	4520
	11th to 20th	Night	46% 6% 14% 21% 11% 1	4045
	21st to end	Night	43% 7% 10% 21% 15% 4	3950
June	1st to 10th	Night	32% 7% 13% 24% 23% 2	1600
	11th to 20th	Night	23% 5% 13% 30% 24% 5%	1600
	21st to end	Night	21% 7% 16% 30% 19% 7%	1600
July	1st to 10th	Night	31% 7% 15% 22% 23% 2	3580
	11th to 20th	Night	23% 7% 20% 31% 15% 3	3663
	21st to end	Night	34% 7% 17% 30% 12% 1	4320
August	1st to 10th	Night	18% 5% 16% 37% 23% 2	3121
	11th to 20th	Night	25% 6% 17% 29% 20% 2	3230
	21st to end	Night	21% 5% 10% 33% 27% 3	3586
September	1st to 10th	Night	27% 5% 10% 28% 23% 7%	2000
	11th to 20th	Night	30% 5% 9% 26% 25% 5%	2030
	21st to end	Night	29% 5% 9% 21% 28% 8%	2200
October	1st to 10th	Night	15% 3 5% 18% 37% 23%	3839
	11th to 20th	Night	21% 2 4 16% 38% 19%	3899
	21st to end	Night	27% 3 5% 26% 29% 10%	4252
November	1st to 10th	Night	31% 3 7% 25% 27% 7%	2640
	11th to 20th	Night	31% 3 7% 25% 25% 9%	2730
	21st to end	Night	37% 3 8% 25% 23% 4	2730
December	1st to 10th	Night	36% 3 8% 31% 20% 2	4550
	11th to 20th	Night	42% 3 7% 24% 20% 3	5341
	21st to end	Night	50% 5% 9% 22% 11% 3	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	26% 11% 35% 22% 6% 1	330
	11th to 20th	Day	25% 13% 41% 18% 4	330
	21st to end	Day	20% 11% 45% 19% 6%	363
February	1st to 10th	Day	26% 12% 35% 18% 8% 1	330
	11th to 20th	Day	29% 17% 33% 18% 3 1	330
	21st to end	Day	27% 16% 34% 18% 5%	273
March	1st to 10th	Day	22% 14% 35% 21% 7%	330
	11th to 20th	Day	22% 15% 35% 25% 3	330
	21st to end	Day	19% 15% 34% 24% 8% 1	510
April	1st to 10th	Day	17% 12% 35% 26% 10%	504
	11th to 20th	Day	18% 13% 32% 25% 10% 1	492
	21st to end	Day	17% 11% 32% 25% 11% 4	500
May	1st to 10th	Day	16% 12% 28% 30% 12% 2	503
	11th to 20th	Day	13% 7% 24% 29% 18% 9%	527
	21st to end	Day	11% 4 23% 29% 24% 10%	789
June	1st to 10th	Day	9% 4 16% 28% 27% 16%	730
	11th to 20th	Day	5% 2 13% 36% 32% 12%	730
	21st to end	Day	4 1 18% 32% 31% 14%	730
July	1st to 10th	Day	8% 1 10% 25% 32% 24%	721
	11th to 20th	Day	6% 2 9% 27% 38% 19%	718
	21st to end	Day	9% 1 10% 26% 34% 20%	794
August	1st to 10th	Day	7% 2 8% 30% 36% 17%	601
	11th to 20th	Day	14% 1 9% 23% 35% 17%	519
	21st to end	Day	9% 1 7% 21% 38% 24%	583
September	1st to 10th	Day	10% 2 9% 25% 38% 16%	530
	11th to 20th	Day	10% 3 8% 20% 35% 24%	530
	21st to end	Day	16% 4 14% 28% 26% 13%	530
October	1st to 10th	Day	8% 2 17% 34% 30% 9%	381
	11th to 20th	Day	10% 8% 31% 25% 19% 7%	330
	21st to end	Day	24% 10% 29% 21% 13% 3	363
November	1st to 10th	Day	14% 10% 26% 30% 17% 3	330
	11th to 20th	Day	11% 8% 39% 28% 12% 2	330
	21st to end	Day	22% 11% 32% 22% 11% 2	330
December	1st to 10th	Day	17% 13% 37% 24% 8% 2	330
	11th to 20th	Day	24% 12% 32% 21% 11% 2	330
	21st to end	Day	22% 18% 33% 22% 4 1	363
January	1st to 10th	Night	22% 8% 36% 29% 5%	1050
	11th to 20th	Night	22% 11% 40% 24% 3	1050
	21st to end	Night	20% 10% 39% 29% 3	1155
February	1st to 10th	Night	23% 8% 37% 29% 3	955
	11th to 20th	Night	23% 11% 39% 26% 2	823
	21st to end	Night	21% 14% 37% 26% 2	692
March	1st to 10th	Night	20% 11% 33% 30% 5%	840
	11th to 20th	Night	18% 13% 36% 28% 5%	630
	21st to end	Night	17% 11% 35% 28% 9%	693
April	1st to 10th	Night	14% 9% 42% 28% 7%	603
	11th to 20th	Night	14% 10% 33% 32% 11%	593
	21st to end	Night	16% 7% 32% 35% 10% 1	600
May	1st to 10th	Night	16% 7% 27% 36% 13% 1	600
	11th to 20th	Night	15% 6% 23% 38% 16% 2	591
	21st to end	Night	8% 3 19% 41% 25% 3	650
June	1st to 10th	Night	9% 2 14% 41% 31% 4	600
	11th to 20th	Night	4 1 13% 44% 36% 2	600
	21st to end	Night	5% 1 11% 44% 37% 4	600
July	1st to 10th	Night	5% 2 8% 32% 45% 8%	585
	11th to 20th	Night	4 2 8% 30% 48% 8%	582
	21st to end	Night	5% 1 9% 31% 44% 10%	657
August	1st to 10th	Night	3 2 6% 33% 50% 6%	597
	11th to 20th	Night	7% 1 7% 36% 42% 7%	594
	21st to end	Night	6% 1 6% 32% 45% 9%	660
September	1st to 10th	Night	10% 2 7% 34% 41% 7%	600
	11th to 20th	Night	9% 2 8% 33% 41% 7%	630
	21st to end	Night	11% 2 17% 36% 30% 5%	800
October	1st to 10th	Night	8% 3 16% 39% 29% 4	800
	11th to 20th	Night	15% 4 27% 35% 19% 2	800
	21st to end	Night	19% 7% 28% 34% 12% 1	880
November	1st to 10th	Night	14% 5% 27% 37% 16% 1	820
	11th to 20th	Night	14% 6% 33% 36% 11%	840
	21st to end	Night	18% 6% 31% 34% 10% 1	840
December	1st to 10th	Night	22% 8% 29% 33% 7%	945
	11th to 20th	Night	22% 8% 30% 32% 8%	1050
	21st to end	Night	25% 11% 32% 27% 5%	1155

Page generated at 2026-03-30 01:18:42. Version ac07

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