Knox Octagon Barn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knox Octagon Barn clear sky chart from 2005-11-06 to 2024-12-02.

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	15% 9% 3 8% 6% 5% 5% 4 6% 7% 32%	101645
	Night	15% 9% 3 8% 5% 5% 5% 4 6% 7% 33%	98006
Transparency	Day	48% 7% 13% 20% 11% 1	105151
	Night	47% 7% 13% 21% 11% 1	102589
Seeing	Day	21% 18% 30% 20% 9% 2	14878
	Night	20% 17% 31% 24% 7% 1	23983

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	12% 12% 5% 9% 7% 6% 5% 4 7% 7% 26%	2517
	11th to 20th	Day	14% 14% 6% 12% 6% 6% 6% 3 5% 5% 23%	2520
	21st to end	Day	18% 15% 6% 11% 6% 6% 5% 4 5% 5% 20%	2904
February	1st to 10th	Day	14% 12% 4 10% 8% 7% 6% 5% 5% 6% 23%	1710
	11th to 20th	Day	10% 11% 5% 12% 7% 5% 5% 4 7% 7% 27%	1802
	21st to end	Day	15% 11% 5% 11% 6% 5% 5% 3 5% 5% 28%	1570
March	1st to 10th	Day	22% 13% 3 9% 6% 4 4 2 4 5% 27%	3116
	11th to 20th	Day	12% 13% 4 10% 6% 5% 5% 4 6% 6% 29%	3338
	21st to end	Day	18% 10% 4 8% 6% 5% 4 3 4 5% 35%	4130
April	1st to 10th	Day	17% 11% 3 8% 6% 4 3 3 5% 5% 34%	2280
	11th to 20th	Day	16% 9% 3 7% 5% 5% 4 4 5% 5% 36%	2254
	21st to end	Day	19% 8% 3 8% 5% 4 5% 4 5% 6% 32%	2346
May	1st to 10th	Day	23% 11% 3 7% 5% 4 4 3 4 6% 29%	4225
	11th to 20th	Day	17% 7% 3 7% 5% 6% 5% 4 5% 8% 32%	4398
	21st to end	Day	11% 5% 2 6% 5% 5% 6% 5% 7% 10% 38%	4837
June	1st to 10th	Day	16% 6% 2 8% 5% 5% 6% 5% 7% 8% 32%	2660
	11th to 20th	Day	15% 7% 2 7% 5% 5% 6% 5% 6% 9% 33%	2660
	21st to end	Day	14% 8% 3 7% 6% 6% 4 5% 7% 9% 33%	2660
July	1st to 10th	Day	9% 6% 3 8% 6% 6% 6% 6% 8% 9% 33%	4440
	11th to 20th	Day	8% 5% 2 7% 6% 6% 6% 5% 8% 10% 37%	4440
	21st to end	Day	12% 7% 3 8% 6% 6% 5% 5% 7% 8% 34%	4814
August	1st to 10th	Day	16% 6% 3 8% 5% 5% 5% 4 6% 8% 33%	4366
	11th to 20th	Day	11% 7% 3 9% 7% 6% 6% 5% 8% 10% 29%	3743
	21st to end	Day	11% 5% 2 7% 5% 5% 6% 5% 8% 10% 37%	4180
September	1st to 10th	Day	13% 6% 2 6% 5% 5% 6% 4 5% 7% 42%	2280
	11th to 20th	Day	13% 5% 2 5% 3 4 4 4 5% 7% 48%	2209
	21st to end	Day	16% 6% 2 6% 4 4 5% 4 7% 8% 39%	2090
October	1st to 10th	Day	17% 8% 3 7% 5% 5% 4 4 5% 6% 34%	1960
	11th to 20th	Day	14% 8% 2 8% 5% 4 3 4 6% 7% 39%	1900
	21st to end	Day	20% 10% 3 7% 5% 5% 5% 4 5% 8% 29%	1909
November	1st to 10th	Day	12% 11% 3 6% 5% 4 3 3 6% 6% 42%	1761
	11th to 20th	Day	13% 9% 3 8% 6% 5% 5% 4 5% 7% 36%	1800
	21st to end	Day	16% 11% 4 7% 6% 5% 5% 4 6% 6% 31%	1620
December	1st to 10th	Day	16% 14% 4 12% 6% 6% 5% 4 5% 6% 22%	1528
	11th to 20th	Day	20% 11% 3 8% 5% 5% 5% 3 5% 6% 29%	1906
	21st to end	Day	20% 14% 8% 9% 6% 5% 5% 4 5% 6% 20%	2772
January	1st to 10th	Night	14% 12% 4 8% 6% 4 5% 5% 7% 7% 29%	4429
	11th to 20th	Night	12% 14% 4 11% 8% 5% 6% 4 6% 7% 24%	4440
	21st to end	Night	19% 14% 5% 11% 6% 6% 5% 4 5% 5% 21%	4752
February	1st to 10th	Night	14% 12% 4 11% 7% 5% 5% 4 7% 6% 26%	2470
	11th to 20th	Night	10% 11% 4 11% 6% 5% 6% 6% 7% 7% 27%	2262
	21st to end	Night	17% 10% 3 9% 6% 5% 5% 5% 5% 7% 28%	1884
March	1st to 10th	Night	21% 11% 3 7% 5% 5% 5% 4 6% 7% 28%	3724
	11th to 20th	Night	14% 11% 3 8% 6% 6% 5% 5% 5% 6% 32%	3617
	21st to end	Night	13% 12% 3 9% 6% 6% 5% 4 5% 4 33%	3501
April	1st to 10th	Night	17% 10% 3 8% 6% 5% 5% 4 5% 6% 30%	1900
	11th to 20th	Night	19% 8% 2 8% 5% 4 3 3 6% 7% 35%	1875
	21st to end	Night	19% 8% 2 7% 4 4 4 4 5% 6% 37%	1834
May	1st to 10th	Night	24% 9% 3 8% 4 5% 5% 3 4 6% 30%	2743
	11th to 20th	Night	15% 10% 3 8% 6% 5% 5% 4 5% 7% 32%	2495
	21st to end	Night	12% 6% 2 7% 5% 5% 6% 5% 7% 8% 37%	2738
June	1st to 10th	Night	15% 8% 2 6% 4 4 4 4 5% 7% 40%	1520
	11th to 20th	Night	15% 5% 2 5% 4 4 5% 4 7% 10% 40%	1520
	21st to end	Night	11% 4 1 6% 5% 6% 4 4 6% 9% 43%	1520
July	1st to 10th	Night	9% 5% 3 8% 7% 6% 5% 4 6% 8% 39%	2520
	11th to 20th	Night	10% 7% 2 6% 5% 4 6% 4 6% 8% 42%	2520
	21st to end	Night	11% 7% 3 7% 6% 4 5% 4 6% 6% 40%	2739
August	1st to 10th	Night	17% 7% 2 7% 4 5% 5% 4 6% 7% 36%	2559
	11th to 20th	Night	13% 8% 3 7% 5% 4 5% 4 6% 7% 38%	3052
	21st to end	Night	12% 5% 2 5% 4 5% 5% 4 6% 8% 45%	3476
September	1st to 10th	Night	13% 6% 3 5% 4 4 4 4 6% 6% 45%	1900
	11th to 20th	Night	13% 4 1 5% 3 3 4 3 5% 6% 52%	1971
	21st to end	Night	13% 5% 2 6% 4 5% 4 4 6% 7% 44%	2090
October	1st to 10th	Night	18% 8% 3 7% 5% 3 4 3 6% 6% 37%	2217
	11th to 20th	Night	15% 7% 3 7% 4 4 4 4 5% 7% 40%	2280
	21st to end	Night	20% 9% 2 8% 3 5% 5% 4 6% 6% 32%	2688
November	1st to 10th	Night	14% 9% 3 8% 5% 4 3 4 5% 6% 41%	2537
	11th to 20th	Night	15% 8% 3 6% 6% 5% 5% 4 6% 6% 34%	2600
	21st to end	Night	14% 9% 3 8% 6% 5% 5% 4 5% 7% 34%	2775
December	1st to 10th	Night	16% 12% 3 8% 6% 6% 5% 5% 7% 7% 25%	2686
	11th to 20th	Night	18% 9% 3 10% 5% 5% 5% 4 6% 6% 27%	3288
	21st to end	Night	23% 12% 8% 8% 5% 4 4 3 5% 6% 22%	4884

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	54% 4 17% 18% 6% 1	2518
	11th to 20th	Day	60% 6% 13% 15% 6% 1	2520
	21st to end	Day	62% 6% 13% 12% 5% 1	2904
February	1st to 10th	Day	58% 7% 13% 14% 7% 1	1710
	11th to 20th	Day	53% 5% 13% 19% 9% 2	1811
	21st to end	Day	54% 6% 12% 16% 11% 1	1570
March	1st to 10th	Day	58% 5% 12% 15% 9% 1	3119
	11th to 20th	Day	50% 6% 17% 17% 8% 2	3338
	21st to end	Day	50% 4 9% 16% 18% 3	4130
April	1st to 10th	Day	51% 4 9% 21% 12% 2	2280
	11th to 20th	Day	48% 5% 11% 20% 14% 2	2254
	21st to end	Day	50% 6% 11% 18% 12% 3	2346
May	1st to 10th	Day	54% 7% 10% 17% 11% 1	4239
	11th to 20th	Day	47% 8% 14% 20% 9% 1	4402
	21st to end	Day	36% 10% 14% 25% 13% 1	4837
June	1st to 10th	Day	47% 9% 13% 19% 11% 1	2660
	11th to 20th	Day	46% 8% 15% 20% 11% 1	2660
	21st to end	Day	47% 8% 13% 21% 11% 1	2660
July	1st to 10th	Day	45% 7% 13% 23% 12% 1	4370
	11th to 20th	Day	40% 7% 15% 25% 11%	4365
	21st to end	Day	48% 6% 14% 21% 11% 1	4661
August	1st to 10th	Day	49% 7% 14% 19% 10% 1	4352
	11th to 20th	Day	47% 8% 16% 25% 5%	3779
	21st to end	Day	38% 9% 13% 30% 10% 1	4180
September	1st to 10th	Day	40% 7% 12% 24% 16% 1	2280
	11th to 20th	Day	36% 6% 12% 26% 19% 1	2209
	21st to end	Day	40% 9% 11% 24% 14% 2	2090
October	1st to 10th	Day	45% 7% 8% 22% 18% 1	3259
	11th to 20th	Day	38% 6% 11% 25% 16% 4	3140
	21st to end	Day	37% 6% 15% 26% 13% 3	3121
November	1st to 10th	Day	42% 6% 13% 24% 13% 1	1761
	11th to 20th	Day	47% 5% 12% 19% 15% 2	1800
	21st to end	Day	51% 6% 16% 19% 7% 1	1620
December	1st to 10th	Day	62% 6% 11% 14% 6% 1	1528
	11th to 20th	Day	54% 5% 18% 16% 6% 1	1906
	21st to end	Day	64% 7% 11% 14% 4	2772
January	1st to 10th	Night	48% 8% 17% 17% 9% 1	4429
	11th to 20th	Night	55% 6% 15% 15% 8% 1	4440
	21st to end	Night	63% 5% 11% 13% 6% 1	4752
February	1st to 10th	Night	54% 8% 12% 17% 8% 1	2470
	11th to 20th	Night	52% 6% 15% 16% 9% 1	2264
	21st to end	Night	52% 5% 14% 17% 9% 2	1884
March	1st to 10th	Night	52% 7% 12% 18% 9% 1	3734
	11th to 20th	Night	49% 7% 14% 22% 7% 1	3618
	21st to end	Night	50% 4 10% 17% 16% 3	3501
April	1st to 10th	Night	51% 6% 12% 18% 11% 2	1900
	11th to 20th	Night	48% 5% 12% 19% 15% 1	1875
	21st to end	Night	46% 6% 12% 18% 15% 3	1834
May	1st to 10th	Night	54% 7% 11% 15% 11% 2	2749
	11th to 20th	Night	49% 9% 13% 20% 8% 1	2496
	21st to end	Night	39% 10% 15% 20% 14% 1	2739
June	1st to 10th	Night	42% 7% 11% 24% 13% 2	1520
	11th to 20th	Night	38% 9% 15% 26% 12%	1520
	21st to end	Night	37% 9% 15% 25% 14% 1	1520
July	1st to 10th	Night	40% 7% 15% 22% 15% 1	2480
	11th to 20th	Night	38% 7% 16% 26% 13%	2472
	21st to end	Night	42% 7% 11% 27% 11% 1	2651
August	1st to 10th	Night	46% 7% 14% 24% 9%	2549
	11th to 20th	Night	43% 6% 18% 24% 9%	3082
	21st to end	Night	33% 8% 12% 36% 11% 1	3476
September	1st to 10th	Night	38% 7% 12% 27% 15% 1	1900
	11th to 20th	Night	31% 7% 12% 27% 23% 1	1971
	21st to end	Night	39% 7% 12% 24% 17% 1	2090
October	1st to 10th	Night	47% 7% 11% 23% 12%	3698
	11th to 20th	Night	34% 7% 12% 24% 19% 4	3779
	21st to end	Night	40% 5% 15% 28% 11% 1	4426
November	1st to 10th	Night	42% 6% 12% 21% 17% 2	2537
	11th to 20th	Night	47% 5% 13% 19% 13% 2	2600
	21st to end	Night	47% 7% 18% 20% 7% 1	2775
December	1st to 10th	Night	54% 7% 17% 16% 7%	2686
	11th to 20th	Night	53% 6% 16% 15% 9% 1	3288
	21st to end	Night	61% 7% 12% 15% 5%	4884

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% 26% 31% 13% 3 1	180
	11th to 20th	Day	32% 28% 27% 12% 2 1	180
	21st to end	Day	21% 30% 32% 12% 5%	236
February	1st to 10th	Day	29% 31% 30% 9% 1	270
	11th to 20th	Day	27% 31% 32% 10% 1	410
	21st to end	Day	27% 24% 34% 13% 2	382
March	1st to 10th	Day	27% 23% 34% 13% 3	460
	11th to 20th	Day	25% 28% 31% 12% 3 1	460
	21st to end	Day	29% 26% 25% 13% 5% 1	506
April	1st to 10th	Day	29% 28% 23% 13% 6% 1	460
	11th to 20th	Day	26% 28% 24% 13% 7% 2	452
	21st to end	Day	29% 22% 29% 13% 5% 2	460
May	1st to 10th	Day	30% 17% 30% 14% 5% 3	463
	11th to 20th	Day	18% 17% 33% 24% 7% 2	487
	21st to end	Day	16% 12% 32% 26% 12% 3	529
June	1st to 10th	Day	15% 17% 33% 23% 10% 1	490
	11th to 20th	Day	14% 16% 31% 24% 13% 1	490
	21st to end	Day	15% 17% 32% 23% 10% 2	490
July	1st to 10th	Day	10% 11% 29% 31% 16% 3	485
	11th to 20th	Day	12% 6% 32% 33% 13% 3	484
	21st to end	Day	12% 8% 37% 28% 12% 3	532
August	1st to 10th	Day	12% 8% 30% 28% 17% 5%	486
	11th to 20th	Day	13% 9% 29% 29% 15% 5%	479
	21st to end	Day	12% 13% 27% 27% 16% 5%	539
September	1st to 10th	Day	17% 9% 28% 22% 18% 7%	490
	11th to 20th	Day	13% 10% 25% 24% 18% 11%	490
	21st to end	Day	18% 11% 26% 27% 13% 6%	490
October	1st to 10th	Day	23% 13% 28% 20% 14% 3	490
	11th to 20th	Day	18% 20% 28% 24% 8% 2	490
	21st to end	Day	27% 17% 30% 20% 7%	443
November	1st to 10th	Day	24% 18% 25% 21% 11% 1	395
	11th to 20th	Day	25% 23% 29% 17% 5% 1	400
	21st to end	Day	25% 26% 29% 18% 2	220
December	1st to 10th	Day	25% 26% 30% 14% 5%	182
	11th to 20th	Day	30% 26% 34% 8% 2	180
	21st to end	Day	22% 30% 33% 11% 4 1	198
January	1st to 10th	Night	19% 24% 37% 17% 2	760
	11th to 20th	Night	24% 22% 33% 19% 2	760
	21st to end	Night	18% 23% 39% 19% 2	836
February	1st to 10th	Night	21% 23% 38% 16% 1	760
	11th to 20th	Night	21% 25% 37% 17%	743
	21st to end	Night	26% 24% 31% 17% 3	628
March	1st to 10th	Night	24% 22% 36% 16% 2	760
	11th to 20th	Night	24% 24% 34% 16% 3	760
	21st to end	Night	22% 23% 32% 18% 4	836
April	1st to 10th	Night	22% 24% 33% 18% 3	760
	11th to 20th	Night	23% 21% 32% 18% 6%	751
	21st to end	Night	22% 21% 31% 21% 5%	694
May	1st to 10th	Night	24% 17% 32% 21% 6%	518
	11th to 20th	Night	17% 16% 35% 26% 6% 1	374
	21st to end	Night	14% 9% 29% 38% 10% 1	411
June	1st to 10th	Night	17% 10% 32% 30% 10% 1	380
	11th to 20th	Night	17% 8% 29% 36% 10%	380
	21st to end	Night	13% 7% 31% 37% 11% 1	380
July	1st to 10th	Night	10% 5% 28% 42% 15% 1	370
	11th to 20th	Night	14% 5% 23% 42% 15% 1	368
	21st to end	Night	11% 5% 27% 43% 13%	416
August	1st to 10th	Night	12% 4 26% 38% 19% 1	405
	11th to 20th	Night	13% 6% 25% 37% 16% 4	717
	21st to end	Night	15% 7% 24% 36% 18% 1	836
September	1st to 10th	Night	13% 7% 28% 34% 16% 1	760
	11th to 20th	Night	14% 8% 26% 28% 19% 5%	760
	21st to end	Night	16% 8% 29% 32% 14% 2	760
October	1st to 10th	Night	21% 12% 26% 26% 14% 1	760
	11th to 20th	Night	17% 14% 32% 28% 9%	760
	21st to end	Night	26% 16% 30% 23% 4	836
November	1st to 10th	Night	19% 17% 29% 27% 7%	780
	11th to 20th	Night	20% 20% 31% 21% 6% 1	800
	21st to end	Night	21% 22% 29% 23% 5%	800
December	1st to 10th	Night	22% 24% 33% 17% 3	768
	11th to 20th	Night	25% 20% 33% 20% 3	760
	21st to end	Night	27% 24% 30% 17% 2	836

Page generated at 2024-11-29 10:43:04. Version ac07

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