Kilpatrick Point Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kilpatrick Point Observatory clear sky chart from 2005-11-06 to 2025-06-10.

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	14% 8% 3 7% 5% 4 5% 4 6% 7% 37%	119664
	Night	14% 9% 3 6% 4 4 4 3 5% 7% 40%	118569
Transparency	Day	26% 42% 6% 11% 10% 4	123469
	Night	25% 42% 7% 11% 11% 5%	122901
Seeing	Day	22% 13% 22% 21% 15% 8%	15665
	Night	20% 10% 18% 28% 20% 4	25744

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% 10% 4 5% 2 2 3 3 4 5% 44%	4056
	11th to 20th	Day	14% 8% 4 8% 3 3 2 2 3 4 48%	4060
	21st to end	Day	20% 11% 3 6% 3 3 3 2 3 5% 41%	4466
February	1st to 10th	Day	18% 10% 3 7% 4 4 4 4 4 6% 37%	1997
	11th to 20th	Day	23% 10% 2 7% 5% 3 4 3 4 5% 35%	1948
	21st to end	Day	23% 9% 2 6% 4 4 2 3 4 5% 37%	1650
March	1st to 10th	Day	20% 9% 3 7% 4 3 4 3 5% 6% 37%	4679
	11th to 20th	Day	13% 6% 2 5% 3 3 3 3 4 7% 50%	4980
	21st to end	Day	17% 8% 3 7% 4 4 4 3 4 5% 43%	5465
April	1st to 10th	Day	13% 7% 3 6% 5% 5% 5% 4 6% 7% 40%	2222
	11th to 20th	Day	14% 7% 2 7% 5% 4 4 4 5% 6% 42%	2392
	21st to end	Day	14% 7% 3 6% 6% 4 4 4 5% 8% 41%	2600
May	1st to 10th	Day	18% 9% 3 8% 4 5% 5% 4 6% 8% 30%	5862
	11th to 20th	Day	17% 10% 4 10% 7% 6% 6% 5% 6% 7% 23%	5861
	21st to end	Day	16% 9% 3 7% 5% 5% 5% 4 7% 8% 32%	6433
June	1st to 10th	Day	11% 7% 3 9% 6% 6% 6% 4 8% 9% 30%	2587
	11th to 20th	Day	7% 6% 2 7% 7% 7% 7% 6% 8% 9% 34%	2470
	21st to end	Day	9% 6% 2 8% 7% 7% 6% 6% 8% 9% 33%	2470
July	1st to 10th	Day	7% 6% 3 8% 7% 7% 7% 6% 9% 12% 29%	4120
	11th to 20th	Day	11% 7% 3 7% 6% 7% 6% 6% 7% 9% 31%	4120
	21st to end	Day	15% 11% 4 12% 8% 8% 8% 6% 7% 7% 15%	4466
August	1st to 10th	Day	8% 7% 2 8% 6% 6% 7% 5% 8% 10% 32%	4104
	11th to 20th	Day	9% 5% 2 7% 5% 4 7% 5% 8% 13% 34%	3951
	21st to end	Day	8% 5% 2 7% 6% 5% 6% 5% 7% 8% 41%	4156
September	1st to 10th	Day	12% 6% 3 9% 6% 6% 5% 5% 7% 7% 33%	2090
	11th to 20th	Day	14% 7% 3 8% 7% 5% 5% 4 6% 8% 34%	2090
	21st to end	Day	14% 6% 3 7% 4 5% 5% 4 6% 6% 41%	2090
October	1st to 10th	Day	10% 6% 2 5% 4 4 4 3 5% 6% 51%	2090
	11th to 20th	Day	13% 6% 2 5% 3 3 4 3 4 5% 53%	1939
	21st to end	Day	13% 5% 2 5% 4 3 3 3 4 6% 52%	2090
November	1st to 10th	Day	12% 6% 2 4 3 3 4 3 4 6% 54%	1791
	11th to 20th	Day	14% 6% 2 4 3 3 4 4 5% 7% 48%	1800
	21st to end	Day	15% 9% 3 5% 4 4 3 2 5% 5% 45%	1800
December	1st to 10th	Day	21% 7% 2 4 3 2 3 2 4 5% 47%	2930
	11th to 20th	Day	21% 11% 3 6% 4 4 4 3 5% 5% 35%	3373
	21st to end	Day	16% 10% 5% 7% 3 3 4 3 5% 7% 38%	4466
January	1st to 10th	Night	14% 11% 3 5% 3 3 3 3 3 6% 44%	5889
	11th to 20th	Night	18% 9% 3 6% 3 2 3 2 3 5% 45%	5900
	21st to end	Night	17% 13% 3 6% 3 3 3 2 4 5% 43%	6490
February	1st to 10th	Night	16% 10% 3 6% 4 4 3 4 5% 6% 39%	2400
	11th to 20th	Night	22% 11% 3 6% 4 4 4 3 4 4 36%	2338
	21st to end	Night	23% 10% 3 6% 4 4 4 3 4 5% 35%	1980
March	1st to 10th	Night	20% 12% 4 6% 4 4 4 3 4 5% 33%	5172
	11th to 20th	Night	12% 8% 1 5% 3 3 4 3 6% 8% 48%	4980
	21st to end	Night	13% 11% 3 6% 5% 4 4 3 5% 6% 41%	5467
April	1st to 10th	Night	14% 8% 2 5% 4 3 4 3 6% 8% 43%	2193
	11th to 20th	Night	13% 8% 2 6% 4 3 3 2 6% 8% 46%	1955
	21st to end	Night	12% 7% 2 6% 4 4 4 4 6% 7% 44%	1800
May	1st to 10th	Night	16% 10% 3 7% 5% 5% 5% 4 6% 8% 31%	4033
	11th to 20th	Night	19% 13% 3 9% 6% 4 5% 4 5% 8% 26%	4032
	21st to end	Night	14% 8% 3 7% 5% 5% 5% 5% 6% 9% 35%	4421
June	1st to 10th	Night	10% 7% 2 7% 6% 5% 5% 5% 8% 10% 35%	1797
	11th to 20th	Night	6% 6% 2 5% 5% 5% 5% 4 7% 10% 45%	1710
	21st to end	Night	9% 6% 2 6% 5% 4 6% 6% 6% 10% 40%	1710
July	1st to 10th	Night	9% 7% 3 8% 6% 5% 7% 5% 7% 11% 31%	2840
	11th to 20th	Night	8% 6% 3 7% 5% 5% 6% 5% 9% 11% 35%	2840
	21st to end	Night	15% 11% 4 9% 6% 6% 7% 5% 7% 8% 22%	3087
August	1st to 10th	Night	7% 5% 3 7% 6% 5% 5% 5% 8% 13% 35%	2825
	11th to 20th	Night	13% 7% 2 7% 5% 4 4 3 6% 8% 41%	2873
	21st to end	Night	7% 4 2 5% 4 5% 5% 5% 7% 10% 47%	3476
September	1st to 10th	Night	9% 7% 2 7% 5% 5% 6% 4 8% 8% 38%	2080
	11th to 20th	Night	11% 7% 2 6% 5% 5% 5% 5% 6% 7% 40%	2090
	21st to end	Night	10% 6% 2 6% 4 4 5% 4 6% 7% 46%	2090
October	1st to 10th	Night	11% 7% 2 5% 3 2 3 3 4 6% 54%	2090
	11th to 20th	Night	13% 5% 3 5% 4 4 3 3 4 6% 50%	2238
	21st to end	Night	12% 7% 2 5% 4 3 3 3 4 5% 54%	2508
November	1st to 10th	Night	11% 6% 2 5% 3 3 3 3 5% 7% 51%	2503
	11th to 20th	Night	15% 8% 2 5% 3 3 4 3 4 6% 48%	2600
	21st to end	Night	16% 9% 2 6% 4 3 4 3 5% 6% 43%	2600
December	1st to 10th	Night	20% 9% 2 4 3 3 3 3 4 5% 44%	4250
	11th to 20th	Night	22% 11% 4 6% 3 3 3 3 4 5% 35%	4822
	21st to end	Night	16% 12% 5% 8% 4 4 4 4 5% 6% 33%	6490

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	28% 30% 2 12% 23% 6%	4057
	11th to 20th	Day	23% 32% 3 10% 21% 12%	4060
	21st to end	Day	33% 30% 4 10% 14% 9%	4466
February	1st to 10th	Day	18% 62% 3 8% 7% 2	1997
	11th to 20th	Day	22% 61% 2 6% 7% 2	1958
	21st to end	Day	19% 62% 2 4 9% 3	1650
March	1st to 10th	Day	38% 30% 4 9% 12% 8%	4679
	11th to 20th	Day	21% 30% 3 12% 17% 18%	4980
	21st to end	Day	31% 29% 5% 19% 11% 5%	5465
April	1st to 10th	Day	19% 63% 4 6% 7% 1	2222
	11th to 20th	Day	18% 63% 4 7% 6% 1	2392
	21st to end	Day	16% 62% 5% 9% 6% 1	2600
May	1st to 10th	Day	38% 32% 11% 14% 6%	5897
	11th to 20th	Day	44% 33% 8% 13% 3	5865
	21st to end	Day	36% 31% 8% 15% 10% 1	6447
June	1st to 10th	Day	19% 64% 6% 8% 3	2587
	11th to 20th	Day	15% 68% 7% 6% 4	2470
	21st to end	Day	17% 66% 7% 7% 3	2470
July	1st to 10th	Day	26% 45% 14% 13% 2	4055
	11th to 20th	Day	28% 45% 15% 10% 2	4051
	21st to end	Day	49% 39% 6% 4 2	4324
August	1st to 10th	Day	26% 43% 13% 15% 4	4091
	11th to 20th	Day	18% 44% 17% 10% 9% 2	3990
	21st to end	Day	18% 42% 10% 20% 9% 1	4156
September	1st to 10th	Day	17% 62% 5% 8% 7% 1	2090
	11th to 20th	Day	19% 62% 5% 8% 6%	2090
	21st to end	Day	18% 62% 7% 7% 6% 1	2090
October	1st to 10th	Day	14% 38% 5% 12% 23% 8%	3480
	11th to 20th	Day	10% 37% 2 11% 17% 23%	3205
	21st to end	Day	15% 39% 5% 16% 14% 11%	3428
November	1st to 10th	Day	19% 56% 3 7% 11% 4	1791
	11th to 20th	Day	16% 57% 3 9% 11% 4	1800
	21st to end	Day	17% 58% 4 8% 12% 2	1800
December	1st to 10th	Day	25% 36% 2 11% 18% 8%	2930
	11th to 20th	Day	34% 32% 3 10% 14% 5%	3370
	21st to end	Day	31% 32% 7% 19% 11% 1	4466
January	1st to 10th	Night	29% 28% 4 9% 22% 8%	5889
	11th to 20th	Night	27% 29% 3 12% 18% 12%	5900
	21st to end	Night	30% 31% 4 8% 18% 9%	6490
February	1st to 10th	Night	18% 62% 4 8% 6% 2	2400
	11th to 20th	Night	23% 60% 3 6% 6% 2	2339
	21st to end	Night	19% 62% 3 6% 6% 4	1980
March	1st to 10th	Night	37% 34% 4 9% 12% 4	5172
	11th to 20th	Night	21% 30% 4 14% 15% 15%	4980
	21st to end	Night	32% 30% 6% 17% 11% 5%	5467
April	1st to 10th	Night	17% 62% 5% 7% 7% 2	2193
	11th to 20th	Night	17% 63% 5% 8% 6% 1	1955
	21st to end	Night	15% 64% 5% 11% 5% 1	1800
May	1st to 10th	Night	38% 32% 11% 15% 4	4060
	11th to 20th	Night	43% 32% 9% 11% 4	4033
	21st to end	Night	33% 32% 11% 15% 8%	4429
June	1st to 10th	Night	17% 65% 7% 7% 3 1	1797
	11th to 20th	Night	11% 68% 9% 9% 3	1710
	21st to end	Night	14% 65% 9% 9% 3	1710
July	1st to 10th	Night	27% 43% 16% 13% 1	2795
	11th to 20th	Night	22% 44% 18% 14% 1	2786
	21st to end	Night	44% 41% 7% 5% 2	2988
August	1st to 10th	Night	25% 41% 19% 13% 2	2814
	11th to 20th	Night	22% 43% 16% 11% 8%	2900
	21st to end	Night	12% 42% 14% 24% 8% 1	3476
September	1st to 10th	Night	16% 62% 6% 8% 7% 1	2080
	11th to 20th	Night	15% 64% 6% 8% 6%	2090
	21st to end	Night	16% 62% 7% 8% 6% 1	2090
October	1st to 10th	Night	12% 40% 7% 13% 23% 6%	3480
	11th to 20th	Night	11% 37% 3 11% 19% 19%	3711
	21st to end	Night	15% 39% 5% 15% 16% 11%	4120
November	1st to 10th	Night	19% 57% 4 9% 8% 3	2503
	11th to 20th	Night	17% 58% 3 7% 10% 6%	2600
	21st to end	Night	17% 57% 4 9% 11% 2	2600
December	1st to 10th	Night	26% 36% 3 10% 17% 8%	4250
	11th to 20th	Night	33% 36% 3 9% 14% 5%	4824
	21st to end	Night	34% 31% 8% 14% 11% 1	6490

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% 23% 30% 8% 2	300
	11th to 20th	Day	39% 23% 22% 13% 4	300
	21st to end	Day	35% 26% 27% 9% 3	330
February	1st to 10th	Day	31% 24% 33% 10% 1	300
	11th to 20th	Day	47% 24% 23% 5% 1	300
	21st to end	Day	41% 27% 26% 6%	249
March	1st to 10th	Day	35% 17% 28% 15% 5%	382
	11th to 20th	Day	31% 18% 25% 19% 5% 1	500
	21st to end	Day	30% 21% 25% 18% 5% 1	550
April	1st to 10th	Day	26% 19% 26% 19% 10% 1	500
	11th to 20th	Day	20% 24% 22% 22% 10% 2	492
	21st to end	Day	22% 15% 23% 23% 13% 3	500
May	1st to 10th	Day	23% 21% 22% 18% 11% 5%	503
	11th to 20th	Day	20% 13% 23% 21% 15% 8%	527
	21st to end	Day	19% 10% 22% 21% 16% 12%	573
June	1st to 10th	Day	15% 6% 22% 26% 20% 11%	526
	11th to 20th	Day	9% 5% 20% 25% 23% 17%	490
	21st to end	Day	14% 5% 24% 25% 19% 14%	490
July	1st to 10th	Day	12% 5% 14% 26% 26% 17%	485
	11th to 20th	Day	10% 4 14% 26% 24% 22%	484
	21st to end	Day	12% 4 13% 23% 26% 22%	532
August	1st to 10th	Day	19% 5% 17% 21% 19% 19%	486
	11th to 20th	Day	16% 5% 14% 24% 25% 15%	479
	21st to end	Day	16% 2 14% 22% 28% 19%	539
September	1st to 10th	Day	12% 4 13% 25% 32% 14%	490
	11th to 20th	Day	17% 7% 14% 22% 29% 12%	490
	21st to end	Day	17% 8% 15% 27% 25% 8%	490
October	1st to 10th	Day	15% 7% 20% 30% 20% 8%	490
	11th to 20th	Day	17% 13% 24% 24% 19% 3	490
	21st to end	Day	20% 11% 24% 26% 16% 2	539
November	1st to 10th	Day	20% 12% 31% 22% 10% 4	329
	11th to 20th	Day	24% 20% 30% 19% 6%	300
	21st to end	Day	21% 22% 34% 16% 7% 1	300
December	1st to 10th	Day	36% 20% 28% 12% 3 1	300
	11th to 20th	Day	32% 17% 29% 17% 5% 1	300
	21st to end	Day	32% 19% 32% 13% 4	330
January	1st to 10th	Night	31% 14% 27% 23% 5%	800
	11th to 20th	Night	29% 17% 25% 23% 7%	800
	21st to end	Night	25% 17% 31% 25% 3	880
February	1st to 10th	Night	24% 15% 28% 29% 5%	800
	11th to 20th	Night	31% 17% 29% 21% 2	783
	21st to end	Night	32% 18% 28% 19% 4	660
March	1st to 10th	Night	23% 17% 30% 26% 4	800
	11th to 20th	Night	24% 16% 25% 26% 8% 1	800
	21st to end	Night	24% 15% 26% 26% 8% 1	880
April	1st to 10th	Night	23% 15% 26% 27% 9% 1	793
	11th to 20th	Night	20% 12% 22% 31% 15% 1	593
	21st to end	Night	15% 10% 22% 36% 16% 2	600
May	1st to 10th	Night	16% 10% 21% 31% 20% 2	600
	11th to 20th	Night	18% 7% 15% 30% 25% 4	591
	21st to end	Night	15% 4 10% 31% 33% 6%	650
June	1st to 10th	Night	13% 4 10% 34% 32% 7%	599
	11th to 20th	Night	7% 3 12% 32% 33% 14%	570
	21st to end	Night	11% 2 7% 30% 41% 8%	570
July	1st to 10th	Night	12% 2 7% 23% 46% 10%	555
	11th to 20th	Night	11% 3 7% 20% 44% 15%	552
	21st to end	Night	11% 3 5% 22% 44% 15%	624
August	1st to 10th	Night	12% 3 6% 25% 43% 11%	567
	11th to 20th	Night	13% 2 9% 28% 39% 9%	564
	21st to end	Night	12% 3 7% 23% 43% 13%	627
September	1st to 10th	Night	13% 3 9% 29% 37% 9%	750
	11th to 20th	Night	15% 5% 12% 26% 36% 6%	760
	21st to end	Night	15% 5% 11% 32% 34% 3	760
October	1st to 10th	Night	16% 6% 15% 30% 26% 7%	760
	11th to 20th	Night	17% 8% 19% 33% 21% 2	760
	21st to end	Night	17% 11% 17% 36% 16% 3	836
November	1st to 10th	Night	16% 8% 19% 33% 21% 3	780
	11th to 20th	Night	22% 12% 18% 33% 13% 2	800
	21st to end	Night	23% 13% 18% 33% 13% 1	800
December	1st to 10th	Night	29% 14% 21% 27% 8% 1	800
	11th to 20th	Night	26% 14% 21% 31% 7% 1	800
	21st to end	Night	31% 11% 21% 30% 5%	880

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