North Smoke Tower Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Smoke Tower Site clear sky chart from 2005-11-06 to 2025-03-27.

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	10% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	109407
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 44%	109946
Transparency	Day	39% 9% 14% 17% 15% 7%	113188
	Night	37% 8% 14% 18% 17% 8%	114304
Seeing	Day	12% 9% 23% 25% 20% 11%	15799
	Night	12% 7% 23% 32% 21% 4	25935

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	10% 5% 2 5% 3 3 3 3 4 6% 57%	4056
	11th to 20th	Day	19% 7% 3 6% 4 4 3 3 4 6% 41%	4060
	21st to end	Day	10% 6% 2 6% 4 3 4 3 5% 9% 47%	4581
February	1st to 10th	Day	15% 7% 3 5% 4 4 4 4 5% 6% 43%	2000
	11th to 20th	Day	14% 6% 2 6% 4 3 4 4 4 6% 47%	1948
	21st to end	Day	13% 6% 3 6% 4 4 4 3 4 6% 48%	1673
March	1st to 10th	Day	15% 8% 3 7% 5% 4 5% 3 6% 7% 37%	3545
	11th to 20th	Day	8% 4 2 5% 4 4 5% 5% 6% 8% 50%	3590
	21st to end	Day	15% 4 2 5% 4 4 4 4 6% 7% 46%	3881
April	1st to 10th	Day	9% 5% 2 6% 6% 4 5% 4 5% 8% 46%	2090
	11th to 20th	Day	11% 5% 2 8% 6% 5% 5% 4 5% 7% 43%	2090
	21st to end	Day	6% 4 2 4 4 5% 5% 4 6% 7% 52%	2405
May	1st to 10th	Day	8% 4 1 5% 4 5% 5% 4 6% 8% 48%	4082
	11th to 20th	Day	11% 7% 3 8% 6% 6% 6% 4 6% 8% 35%	4081
	21st to end	Day	6% 4 2 5% 5% 5% 5% 4 7% 11% 46%	4476
June	1st to 10th	Day	11% 6% 2 8% 7% 7% 6% 6% 7% 10% 30%	2470
	11th to 20th	Day	6% 6% 2 7% 7% 7% 8% 6% 9% 10% 31%	2470
	21st to end	Day	9% 7% 2 9% 8% 7% 7% 6% 9% 9% 28%	2470
July	1st to 10th	Day	7% 7% 3 11% 8% 8% 9% 7% 10% 12% 19%	4120
	11th to 20th	Day	4 4 3 8% 7% 7% 7% 7% 10% 14% 30%	4120
	21st to end	Day	6% 6% 3 9% 7% 8% 8% 7% 9% 13% 25%	4466
August	1st to 10th	Day	14% 6% 2 8% 6% 7% 7% 7% 9% 10% 23%	4104
	11th to 20th	Day	7% 5% 2 6% 6% 6% 7% 6% 8% 11% 35%	3924
	21st to end	Day	10% 7% 3 9% 7% 7% 7% 6% 8% 11% 25%	3897
September	1st to 10th	Day	11% 8% 3 10% 8% 7% 7% 6% 8% 8% 24%	2090
	11th to 20th	Day	14% 9% 3 10% 7% 7% 7% 5% 7% 8% 24%	2090
	21st to end	Day	12% 6% 3 7% 7% 4 5% 4 6% 7% 38%	2090
October	1st to 10th	Day	13% 7% 2 7% 5% 5% 5% 4 5% 7% 40%	2090
	11th to 20th	Day	7% 5% 2 5% 3 4 5% 3 4 7% 57%	1905
	21st to end	Day	9% 4 1 6% 5% 4 4 4 6% 6% 51%	2090
November	1st to 10th	Day	10% 5% 2 5% 4 3 4 3 5% 7% 50%	1957
	11th to 20th	Day	9% 7% 2 5% 4 4 3 3 5% 6% 51%	1927
	21st to end	Day	11% 6% 3 5% 4 5% 4 3 5% 5% 48%	1800
December	1st to 10th	Day	6% 5% 2 6% 4 4 5% 4 5% 6% 54%	2930
	11th to 20th	Day	14% 8% 3 7% 4 4 4 3 6% 6% 42%	3373
	21st to end	Day	16% 9% 3 7% 5% 4 3 3 4 6% 41%	4466
January	1st to 10th	Night	10% 6% 2 4 3 2 3 3 4 6% 58%	5889
	11th to 20th	Night	16% 7% 2 7% 5% 5% 5% 4 6% 7% 37%	5900
	21st to end	Night	15% 6% 2 5% 3 3 3 3 6% 7% 45%	6371
February	1st to 10th	Night	13% 7% 2 6% 4 3 4 3 4 7% 46%	2400
	11th to 20th	Night	14% 7% 2 6% 4 3 3 3 4 6% 48%	2338
	21st to end	Night	12% 6% 2 6% 4 3 4 3 4 6% 50%	1955
March	1st to 10th	Night	18% 11% 3 7% 4 4 4 3 5% 5% 36%	3528
	11th to 20th	Night	8% 4 2 5% 3 3 4 4 7% 9% 50%	3590
	21st to end	Night	14% 5% 2 4 4 4 4 3 5% 7% 49%	3890
April	1st to 10th	Night	10% 6% 2 4 4 4 4 4 6% 7% 49%	2090
	11th to 20th	Night	9% 6% 3 6% 4 4 3 3 5% 7% 51%	2039
	21st to end	Night	6% 5% 2 4 3 4 3 4 6% 7% 57%	1789
May	1st to 10th	Night	6% 4 2 4 5% 4 5% 4 6% 8% 51%	2813
	11th to 20th	Night	13% 5% 2 7% 4 4 5% 3 6% 9% 42%	2812
	21st to end	Night	5% 3 1 4 3 4 4 3 6% 10% 57%	3079
June	1st to 10th	Night	10% 6% 3 6% 5% 5% 6% 6% 9% 9% 35%	1710
	11th to 20th	Night	6% 4 2 6% 6% 6% 7% 7% 9% 12% 36%	1710
	21st to end	Night	7% 4 2 6% 6% 5% 7% 6% 8% 14% 35%	1710
July	1st to 10th	Night	9% 8% 3 12% 7% 6% 7% 6% 8% 10% 23%	2840
	11th to 20th	Night	5% 6% 3 8% 5% 6% 7% 6% 10% 15% 30%	2840
	21st to end	Night	7% 7% 3 9% 6% 6% 7% 6% 11% 12% 25%	3087
August	1st to 10th	Night	13% 5% 3 8% 5% 6% 8% 6% 9% 10% 28%	2825
	11th to 20th	Night	5% 4 2 5% 4 4 6% 6% 8% 13% 42%	2900
	21st to end	Night	9% 7% 2 8% 5% 6% 6% 5% 7% 12% 34%	3726
September	1st to 10th	Night	11% 7% 3 9% 6% 6% 6% 4 7% 11% 30%	2090
	11th to 20th	Night	13% 7% 3 9% 6% 6% 6% 5% 7% 8% 30%	2090
	21st to end	Night	8% 7% 3 7% 4 5% 4 4 6% 9% 43%	2090
October	1st to 10th	Night	12% 6% 2 7% 4 3 4 3 4 8% 45%	2090
	11th to 20th	Night	7% 5% 2 5% 4 3 3 3 4 6% 58%	2274
	21st to end	Night	7% 4 2 6% 4 4 4 4 6% 7% 53%	2508
November	1st to 10th	Night	11% 4 1 5% 3 3 4 4 7% 7% 51%	2341
	11th to 20th	Night	12% 6% 2 4 4 3 3 3 4 6% 52%	2470
	21st to end	Night	13% 7% 2 6% 4 4 3 3 5% 6% 48%	2600
December	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 4 6% 55%	4250
	11th to 20th	Night	13% 10% 3 6% 4 3 3 3 4 6% 45%	4822
	21st to end	Night	15% 9% 3 7% 4 4 4 3 5% 5% 42%	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	30% 3 6% 15% 31% 15%	4057
	11th to 20th	Day	45% 4 5% 12% 19% 15%	4060
	21st to end	Day	34% 5% 9% 21% 19% 11%	4581
February	1st to 10th	Day	41% 5% 9% 14% 21% 10%	2000
	11th to 20th	Day	38% 5% 8% 15% 22% 13%	1958
	21st to end	Day	37% 5% 9% 16% 18% 15%	1673
March	1st to 10th	Day	44% 8% 9% 17% 15% 7%	3545
	11th to 20th	Day	30% 7% 14% 16% 18% 16%	3590
	21st to end	Day	35% 6% 10% 23% 16% 10%	3881
April	1st to 10th	Day	35% 7% 10% 17% 18% 13%	2090
	11th to 20th	Day	40% 6% 9% 17% 18% 10%	2090
	21st to end	Day	29% 7% 11% 22% 22% 9%	2405
May	1st to 10th	Day	29% 10% 14% 24% 16% 6%	4120
	11th to 20th	Day	42% 9% 13% 21% 13% 2	4085
	21st to end	Day	27% 9% 19% 26% 17% 2	4489
June	1st to 10th	Day	46% 11% 17% 14% 10% 1	2470
	11th to 20th	Day	42% 13% 18% 20% 7%	2470
	21st to end	Day	47% 14% 19% 14% 5%	2470
July	1st to 10th	Day	51% 17% 23% 8% 1	4055
	11th to 20th	Day	38% 15% 35% 9% 2	4051
	21st to end	Day	44% 17% 27% 10% 2	4324
August	1st to 10th	Day	49% 14% 24% 11% 2	4091
	11th to 20th	Day	38% 13% 19% 20% 9%	3963
	21st to end	Day	48% 13% 17% 20% 2	3897
September	1st to 10th	Day	53% 13% 15% 11% 6% 2	2090
	11th to 20th	Day	53% 12% 14% 13% 6% 1	2090
	21st to end	Day	44% 8% 12% 17% 16% 4	2090
October	1st to 10th	Day	50% 5% 8% 10% 15% 12%	3480
	11th to 20th	Day	19% 4 6% 16% 37% 18%	3145
	21st to end	Day	24% 4 7% 17% 36% 12%	3428
November	1st to 10th	Day	34% 5% 10% 19% 19% 13%	1957
	11th to 20th	Day	34% 5% 9% 17% 24% 12%	1927
	21st to end	Day	37% 5% 9% 17% 23% 9%	1800
December	1st to 10th	Day	31% 4 9% 20% 24% 12%	2930
	11th to 20th	Day	42% 5% 8% 19% 19% 8%	3370
	21st to end	Day	46% 4 6% 17% 22% 5%	4466
January	1st to 10th	Night	28% 4 7% 13% 34% 14%	5889
	11th to 20th	Night	46% 4 6% 14% 21% 8%	5900
	21st to end	Night	38% 6% 9% 17% 19% 11%	6371
February	1st to 10th	Night	39% 5% 9% 15% 21% 11%	2400
	11th to 20th	Night	38% 5% 9% 17% 18% 14%	2339
	21st to end	Night	36% 5% 9% 19% 18% 13%	1955
March	1st to 10th	Night	49% 6% 11% 14% 12% 8%	3528
	11th to 20th	Night	28% 6% 15% 19% 18% 13%	3590
	21st to end	Night	35% 6% 11% 18% 19% 11%	3890
April	1st to 10th	Night	32% 7% 14% 17% 18% 11%	2090
	11th to 20th	Night	33% 5% 10% 23% 20% 9%	2039
	21st to end	Night	25% 7% 13% 26% 21% 8%	1789
May	1st to 10th	Night	26% 12% 17% 25% 15% 5%	2840
	11th to 20th	Night	36% 10% 18% 23% 11% 2	2813
	21st to end	Night	20% 9% 17% 32% 20% 2	3087
June	1st to 10th	Night	38% 13% 20% 19% 9%	1710
	11th to 20th	Night	35% 14% 24% 20% 7%	1710
	21st to end	Night	36% 15% 25% 18% 5% 1	1710
July	1st to 10th	Night	51% 15% 24% 9% 1 1	2795
	11th to 20th	Night	39% 18% 32% 9% 3	2786
	21st to end	Night	44% 17% 26% 11% 2	2988
August	1st to 10th	Night	46% 15% 28% 10% 2	2814
	11th to 20th	Night	28% 14% 25% 23% 9%	2927
	21st to end	Night	41% 11% 24% 20% 3	3726
September	1st to 10th	Night	46% 13% 20% 14% 6% 2	2090
	11th to 20th	Night	49% 14% 14% 16% 6% 1	2090
	21st to end	Night	36% 8% 18% 20% 13% 4	2090
October	1st to 10th	Night	48% 7% 10% 13% 13% 10%	3480
	11th to 20th	Night	20% 4 6% 19% 32% 19%	3773
	21st to end	Night	23% 4 9% 19% 32% 13%	4120
November	1st to 10th	Night	30% 6% 11% 22% 17% 13%	2341
	11th to 20th	Night	34% 5% 9% 16% 24% 11%	2470
	21st to end	Night	37% 5% 10% 18% 19% 11%	2600
December	1st to 10th	Night	32% 4 9% 19% 20% 16%	4250
	11th to 20th	Night	42% 6% 8% 19% 17% 9%	4824
	21st to end	Night	44% 5% 9% 17% 20% 4	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	13% 21% 48% 14% 4	300
	11th to 20th	Day	15% 15% 43% 19% 7% 2	300
	21st to end	Day	20% 23% 40% 14% 3	330
February	1st to 10th	Day	21% 14% 36% 22% 6% 1	300
	11th to 20th	Day	21% 19% 41% 14% 4 1	300
	21st to end	Day	14% 17% 40% 24% 4	272
March	1st to 10th	Day	16% 17% 32% 26% 8%	500
	11th to 20th	Day	15% 17% 33% 22% 10% 3	500
	21st to end	Day	15% 16% 34% 23% 11% 2	530
April	1st to 10th	Day	14% 15% 33% 22% 14% 2	460
	11th to 20th	Day	10% 14% 33% 25% 13% 4	452
	21st to end	Day	8% 11% 25% 32% 15% 8%	460
May	1st to 10th	Day	6% 10% 27% 28% 20% 8%	463
	11th to 20th	Day	7% 6% 24% 27% 24% 12%	487
	21st to end	Day	10% 3 14% 29% 29% 14%	529
June	1st to 10th	Day	12% 3 13% 31% 23% 17%	490
	11th to 20th	Day	7% 5% 14% 26% 28% 21%	490
	21st to end	Day	8% 3 8% 25% 33% 22%	490
July	1st to 10th	Day	8% 1 8% 22% 34% 27%	485
	11th to 20th	Day	7% 2 5% 19% 38% 29%	484
	21st to end	Day	8% 3 7% 25% 35% 22%	532
August	1st to 10th	Day	14% 3 9% 17% 33% 23%	486
	11th to 20th	Day	8% 3 4 19% 34% 32%	479
	21st to end	Day	11% 3 10% 24% 32% 21%	539
September	1st to 10th	Day	13% 3 10% 24% 27% 23%	490
	11th to 20th	Day	16% 4 12% 29% 28% 11%	490
	21st to end	Day	14% 3 11% 28% 31% 12%	490
October	1st to 10th	Day	14% 6% 27% 28% 18% 6%	490
	11th to 20th	Day	7% 7% 23% 35% 21% 7%	490
	21st to end	Day	9% 7% 27% 35% 19% 3	539
November	1st to 10th	Day	16% 6% 27% 29% 19% 3	495
	11th to 20th	Day	15% 12% 35% 24% 11% 3	427
	21st to end	Day	12% 19% 36% 23% 8% 2	300
December	1st to 10th	Day	12% 19% 32% 23% 10% 4	300
	11th to 20th	Day	19% 18% 35% 22% 6%	300
	21st to end	Day	17% 13% 35% 27% 6% 2	330
January	1st to 10th	Night	16% 14% 34% 29% 7%	800
	11th to 20th	Night	14% 12% 30% 34% 10% 1	800
	21st to end	Night	17% 15% 37% 26% 4	880
February	1st to 10th	Night	16% 12% 30% 32% 9% 1	800
	11th to 20th	Night	17% 16% 31% 30% 7%	783
	21st to end	Night	15% 13% 34% 35% 3	660
March	1st to 10th	Night	13% 14% 32% 35% 7%	800
	11th to 20th	Night	13% 10% 35% 30% 11% 1	800
	21st to end	Night	11% 13% 33% 32% 11%	863
April	1st to 10th	Night	12% 11% 33% 33% 10%	760
	11th to 20th	Night	12% 11% 34% 32% 11%	751
	21st to end	Night	7% 7% 29% 40% 17% 1	649
May	1st to 10th	Night	5% 3 28% 46% 17% 1	570
	11th to 20th	Night	8% 4 22% 40% 24% 2	561
	21st to end	Night	7% 2 13% 40% 34% 3	617
June	1st to 10th	Night	11% 2 14% 38% 30% 5%	570
	11th to 20th	Night	6% 2 10% 34% 36% 12%	570
	21st to end	Night	8% 2 9% 27% 43% 11%	570
July	1st to 10th	Night	6% 2 7% 24% 43% 18%	555
	11th to 20th	Night	7% 1 4 21% 49% 18%	552
	21st to end	Night	5% 1 7% 28% 49% 10%	624
August	1st to 10th	Night	8% 1 5% 25% 48% 12%	567
	11th to 20th	Night	7% 1 5% 21% 49% 18%	564
	21st to end	Night	13% 2 9% 26% 36% 13%	773
September	1st to 10th	Night	13% 2 11% 27% 34% 12%	760
	11th to 20th	Night	14% 3 14% 30% 32% 6%	760
	21st to end	Night	13% 2 13% 35% 32% 6%	760
October	1st to 10th	Night	15% 2 22% 35% 23% 3	760
	11th to 20th	Night	8% 6% 24% 36% 25% 1	760
	21st to end	Night	7% 6% 25% 38% 21% 2	836
November	1st to 10th	Night	11% 6% 28% 37% 17% 1	780
	11th to 20th	Night	14% 9% 30% 31% 16% 1	800
	21st to end	Night	14% 9% 30% 32% 15%	800
December	1st to 10th	Night	15% 9% 27% 33% 15% 1	800
	11th to 20th	Night	15% 10% 28% 33% 14%	800
	21st to end	Night	17% 12% 28% 31% 12%	880

Page generated at 2025-03-24 09:04:28. Version ac07

Copyright © 2025 Attilla Danko.