Banks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Banks clear sky chart from 2005-11-06 to 2024-11-04.

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	9% 9% 3 6% 4 4 4 3 5% 6% 49%	105149
	Night	11% 10% 3 6% 4 4 4 3 5% 6% 47%	102536
Transparency	Day	34% 6% 10% 18% 19% 13%	104893
	Night	37% 6% 11% 19% 17% 10%	102381
Seeing	Day	13% 11% 28% 30% 15% 3	14424
	Night	16% 4 18% 39% 21% 2	23710

By Month

Percentage Cloud Cover SW (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% 23% 7% 8% 6% 5% 4 4 4 6% 21%	2539
	11th to 20th	Day	15% 19% 7% 8% 5% 5% 4 3 5% 5% 24%	2540
	21st to end	Day	19% 20% 4 8% 4 3 3 3 4 7% 24%	2794
February	1st to 10th	Day	16% 18% 5% 9% 6% 4 4 2 4 5% 28%	1649
	11th to 20th	Day	13% 19% 4 7% 6% 4 4 3 5% 6% 28%	1850
	21st to end	Day	13% 19% 6% 10% 5% 5% 4 5% 5% 5% 23%	1570
March	1st to 10th	Day	11% 18% 8% 9% 6% 4 4 3 4 6% 27%	3138
	11th to 20th	Day	9% 11% 3 6% 4 3 3 3 3 4 51%	3360
	21st to end	Day	13% 15% 5% 11% 6% 7% 6% 4 6% 6% 20%	3998
April	1st to 10th	Day	13% 15% 4 8% 6% 5% 5% 4 5% 6% 31%	2280
	11th to 20th	Day	10% 12% 3 7% 4 5% 5% 5% 4 7% 38%	2304
	21st to end	Day	11% 10% 3 7% 5% 5% 4 3 6% 7% 40%	2470
May	1st to 10th	Day	8% 13% 3 8% 5% 4 4 4 5% 5% 40%	4110
	11th to 20th	Day	7% 5% 2 4 4 3 3 3 5% 6% 59%	4222
	21st to end	Day	8% 8% 2 5% 4 5% 5% 3 7% 7% 45%	4813
June	1st to 10th	Day	11% 7% 2 6% 5% 5% 6% 5% 6% 7% 38%	2660
	11th to 20th	Day	11% 5% 2 4 4 4 3 4 6% 8% 49%	2660
	21st to end	Day	4 3 1 4 3 3 3 4 4 5% 67%	2660
July	1st to 10th	Day	1 1 1 2 1 2 2 2 3 4 81%	4420
	11th to 20th	Day	2 1 1 2 2 2 3 2 3 4 77%	4420
	21st to end	Day	3 2 1 3 2 2 3 2 3 5% 75%	4790
August	1st to 10th	Day	5% 4 2 6% 3 3 4 3 4 6% 61%	4248
	11th to 20th	Day	2 1 1 2 2 2 2 2 3 5% 77%	4028
	21st to end	Day	3 3 1 3 2 2 3 2 3 4 73%	4225
September	1st to 10th	Day	4 2 1 2 2 3 2 3 4 5% 72%	2280
	11th to 20th	Day	7% 4 2 4 3 3 3 3 5% 6% 60%	2104
	21st to end	Day	7% 4 2 3 3 3 3 3 4 5% 62%	2090
October	1st to 10th	Day	7% 5% 2 4 3 2 2 2 4 5% 65%	3490
	11th to 20th	Day	10% 6% 2 6% 3 3 4 3 5% 6% 52%	3020
	21st to end	Day	12% 11% 3 6% 4 4 3 3 5% 6% 43%	3101
November	1st to 10th	Day	18% 12% 3 6% 4 4 4 3 6% 6% 35%	1701
	11th to 20th	Day	16% 14% 3 6% 4 4 4 3 5% 7% 34%	1710
	21st to end	Day	13% 11% 3 8% 5% 4 5% 3 5% 7% 35%	1663
December	1st to 10th	Day	20% 14% 4 7% 3 3 3 3 6% 6% 31%	1520
	11th to 20th	Day	18% 16% 5% 9% 5% 5% 4 3 6% 6% 24%	1928
	21st to end	Day	14% 13% 4 8% 4 4 5% 3 5% 6% 35%	2794
January	1st to 10th	Night	14% 18% 5% 9% 5% 6% 5% 3 5% 6% 24%	4406
	11th to 20th	Night	21% 20% 6% 7% 4 4 4 2 3 5% 24%	4420
	21st to end	Night	20% 17% 4 8% 5% 4 5% 3 5% 6% 23%	4862
February	1st to 10th	Night	16% 16% 4 8% 5% 3 4 3 4 5% 32%	2525
	11th to 20th	Night	14% 16% 4 7% 4 4 4 3 4 5% 35%	2218
	21st to end	Night	14% 18% 6% 7% 4 5% 5% 3 5% 6% 29%	1884
March	1st to 10th	Night	12% 18% 4 6% 5% 4 4 3 5% 6% 34%	3736
	11th to 20th	Night	10% 13% 2 5% 4 3 3 3 4 4 50%	3619
	21st to end	Night	11% 11% 3 9% 5% 5% 6% 5% 7% 9% 29%	3653
April	1st to 10th	Night	13% 11% 2 5% 3 4 4 4 5% 7% 41%	1900
	11th to 20th	Night	12% 8% 3 6% 5% 4 4 4 5% 4 45%	1824
	21st to end	Night	9% 7% 2 5% 4 4 4 3 5% 6% 49%	1710
May	1st to 10th	Night	11% 8% 2 4 3 3 5% 4 6% 7% 47%	2860
	11th to 20th	Night	5% 3 1 5% 3 3 4 3 5% 7% 61%	2660
	21st to end	Night	8% 7% 2 7% 5% 3 4 3 5% 6% 51%	2762
June	1st to 10th	Night	12% 5% 2 5% 4 4 4 4 7% 8% 44%	1520
	11th to 20th	Night	9% 5% 1 4 4 3 3 3 4 5% 57%	1520
	21st to end	Night	3 3 1 3 3 3 4 4 6% 5% 65%	1520
July	1st to 10th	Night	1 1 2 2 2 2 3 4 4 79%	2540
	11th to 20th	Night	1 1 1 2 2 3 2 4 5% 78%	2540
	21st to end	Night	2 3 1 3 3 3 3 3 5% 7% 67%	2761
August	1st to 10th	Night	4 3 1 5% 4 4 5% 4 5% 6% 59%	2684
	11th to 20th	Night	1 1 1 2 2 2 3 3 4 5% 75%	2811
	21st to end	Night	4 3 1 3 1 2 2 2 2 4 75%	3450
September	1st to 10th	Night	3 2 1 3 2 2 2 2 4 4 74%	1900
	11th to 20th	Night	6% 4 1 5% 3 3 3 3 4 6% 61%	2076
	21st to end	Night	8% 4 1 4 2 2 3 3 4 5% 66%	2090
October	1st to 10th	Night	5% 3 1 4 3 3 3 2 4 5% 67%	3490
	11th to 20th	Night	9% 5% 1 4 3 4 3 3 4 6% 58%	3907
	21st to end	Night	11% 8% 2 6% 4 4 4 4 6% 7% 45%	4457
November	1st to 10th	Night	18% 9% 2 6% 4 4 3 3 5% 7% 39%	2450
	11th to 20th	Night	20% 9% 3 6% 5% 3 4 4 5% 6% 36%	2470
	21st to end	Night	14% 12% 3 6% 4 4 5% 3 4 5% 40%	2513
December	1st to 10th	Night	15% 15% 3 6% 5% 5% 5% 4 5% 6% 32%	2660
	11th to 20th	Night	18% 16% 4 9% 5% 5% 5% 4 4 5% 25%	3276
	21st to end	Night	15% 13% 4 8% 4 4 5% 3 5% 7% 33%	4862

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	61% 12% 16% 10% 1	2539
	11th to 20th	Day	61% 8% 13% 14% 4	2540
	21st to end	Day	59% 10% 18% 11% 2	2794
February	1st to 10th	Day	57% 8% 15% 16% 3 1	1649
	11th to 20th	Day	55% 9% 15% 16% 6%	1860
	21st to end	Day	59% 8% 11% 15% 6% 1	1570
March	1st to 10th	Day	54% 9% 11% 17% 9%	3138
	11th to 20th	Day	35% 7% 9% 35% 13% 1	3360
	21st to end	Day	52% 13% 16% 13% 5%	3998
April	1st to 10th	Day	50% 7% 15% 18% 8% 2	2280
	11th to 20th	Day	43% 6% 14% 22% 14% 2	2307
	21st to end	Day	41% 7% 14% 23% 15%	2470
May	1st to 10th	Day	40% 8% 10% 23% 17% 3	4110
	11th to 20th	Day	23% 5% 9% 29% 26% 9%	4225
	21st to end	Day	32% 9% 14% 29% 13% 2	4814
June	1st to 10th	Day	40% 8% 13% 23% 15% 1	2660
	11th to 20th	Day	31% 6% 10% 22% 23% 8%	2660
	21st to end	Day	19% 4 8% 17% 35% 17%	2660
July	1st to 10th	Day	9% 2 4 9% 20% 55%	4351
	11th to 20th	Day	11% 1 4 6% 22% 56%	4345
	21st to end	Day	13% 2 4 9% 30% 42%	4639
August	1st to 10th	Day	24% 3 7% 9% 26% 31%	4232
	11th to 20th	Day	11% 2 4 13% 44% 26%	4067
	21st to end	Day	16% 2 4 19% 33% 25%	4224
September	1st to 10th	Day	15% 4 6% 17% 32% 26%	2280
	11th to 20th	Day	23% 5% 10% 20% 28% 13%	2104
	21st to end	Day	23% 4 9% 26% 28% 10%	2090
October	1st to 10th	Day	24% 4 7% 17% 39% 9%	3490
	11th to 20th	Day	33% 4 12% 24% 25% 3	3020
	21st to end	Day	41% 6% 9% 25% 19% 1	3101
November	1st to 10th	Day	48% 7% 13% 20% 11% 1	1701
	11th to 20th	Day	49% 8% 17% 20% 6%	1710
	21st to end	Day	48% 6% 16% 18% 10% 1	1663
December	1st to 10th	Day	51% 9% 19% 16% 5% 1	1520
	11th to 20th	Day	59% 11% 15% 13% 3	1928
	21st to end	Day	49% 7% 18% 19% 6%	2794
January	1st to 10th	Night	57% 11% 17% 13% 1 1	4406
	11th to 20th	Night	63% 7% 13% 12% 5%	4420
	21st to end	Night	57% 12% 15% 13% 3	4862
February	1st to 10th	Night	54% 7% 16% 18% 4 1	2525
	11th to 20th	Night	50% 7% 14% 19% 9% 1	2219
	21st to end	Night	54% 8% 11% 17% 8% 1	1884
March	1st to 10th	Night	47% 8% 12% 21% 11% 1	3736
	11th to 20th	Night	37% 6% 8% 30% 18% 1	3619
	21st to end	Night	43% 13% 19% 18% 7%	3653
April	1st to 10th	Night	41% 7% 13% 24% 13% 2	1900
	11th to 20th	Night	39% 7% 13% 23% 16% 2	1824
	21st to end	Night	33% 6% 15% 26% 18% 1	1710
May	1st to 10th	Night	32% 7% 11% 27% 21% 3	2860
	11th to 20th	Night	20% 6% 10% 29% 31% 4	2660
	21st to end	Night	31% 8% 11% 32% 17% 1	2762
June	1st to 10th	Night	34% 9% 14% 28% 14% 1	1520
	11th to 20th	Night	28% 5% 9% 24% 26% 8%	1520
	21st to end	Night	17% 5% 8% 19% 34% 17%	1520
July	1st to 10th	Night	8% 3 4 9% 22% 54%	2500
	11th to 20th	Night	10% 2 4 8% 19% 57%	2492
	21st to end	Night	16% 2 5% 8% 29% 39%	2674
August	1st to 10th	Night	24% 4 7% 8% 28% 30%	2676
	11th to 20th	Night	11% 2 5% 11% 36% 35%	2838
	21st to end	Night	15% 2 4 17% 31% 30%	3450
September	1st to 10th	Night	15% 3 5% 15% 32% 30%	1900
	11th to 20th	Night	24% 4 8% 17% 28% 19%	2076
	21st to end	Night	21% 4 6% 24% 29% 15%	2090
October	1st to 10th	Night	21% 3 7% 19% 33% 18%	3490
	11th to 20th	Night	28% 3 12% 23% 28% 6%	3907
	21st to end	Night	37% 5% 12% 24% 19% 2	4457
November	1st to 10th	Night	44% 6% 13% 21% 15% 2	2450
	11th to 20th	Night	48% 7% 13% 24% 9%	2470
	21st to end	Night	45% 6% 13% 23% 10% 2	2513
December	1st to 10th	Night	50% 8% 18% 14% 9% 1	2660
	11th to 20th	Night	58% 8% 13% 17% 4	3276
	21st to end	Night	49% 9% 20% 16% 6%	4862

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	20% 15% 27% 23% 14% 2	180
	11th to 20th	Day	22% 9% 22% 24% 14% 8%	180
	21st to end	Day	20% 9% 25% 28% 13% 6%	198
February	1st to 10th	Day	25% 10% 32% 18% 13% 2	261
	11th to 20th	Day	23% 13% 30% 24% 9% 1	455
	21st to end	Day	22% 17% 28% 25% 8% 1	382
March	1st to 10th	Day	20% 19% 32% 24% 5%	460
	11th to 20th	Day	19% 13% 28% 25% 13% 2	460
	21st to end	Day	21% 17% 31% 23% 8% 1	506
April	1st to 10th	Day	21% 17% 27% 21% 13% 1	460
	11th to 20th	Day	17% 19% 30% 23% 9% 1	452
	21st to end	Day	14% 19% 30% 25% 10% 1	460
May	1st to 10th	Day	12% 16% 34% 25% 11% 2	463
	11th to 20th	Day	20% 11% 28% 25% 13% 2	488
	21st to end	Day	12% 11% 24% 31% 17% 5%	529
June	1st to 10th	Day	11% 13% 28% 27% 17% 3	490
	11th to 20th	Day	14% 17% 32% 24% 11% 2	490
	21st to end	Day	5% 9% 33% 31% 19% 3	490
July	1st to 10th	Day	3 6% 34% 38% 15% 3	486
	11th to 20th	Day	1 9% 33% 40% 14% 2	484
	21st to end	Day	2 4 30% 41% 19% 3	531
August	1st to 10th	Day	5% 7% 31% 36% 18% 2	487
	11th to 20th	Day	2 6% 27% 38% 23% 3	477
	21st to end	Day	6% 9% 24% 36% 22% 2	539
September	1st to 10th	Day	6% 6% 23% 40% 22% 3	490
	11th to 20th	Day	9% 9% 25% 34% 21% 1	490
	21st to end	Day	8% 8% 28% 34% 18% 4	490
October	1st to 10th	Day	11% 10% 22% 31% 23% 4	490
	11th to 20th	Day	14% 7% 25% 30% 17% 6%	371
	21st to end	Day	18% 12% 22% 32% 13% 4	330
November	1st to 10th	Day	22% 11% 23% 29% 14% 2	279
	11th to 20th	Day	17% 8% 24% 31% 16% 3	270
	21st to end	Day	16% 7% 24% 30% 19% 4	248
December	1st to 10th	Day	34% 7% 17% 17% 18% 7%	180
	11th to 20th	Day	28% 7% 24% 28% 12% 2	180
	21st to end	Day	19% 13% 24% 29% 14% 3	198
January	1st to 10th	Night	26% 5% 19% 32% 16% 3	760
	11th to 20th	Night	25% 6% 18% 28% 19% 4	760
	21st to end	Night	22% 3 18% 33% 21% 3	836
February	1st to 10th	Night	23% 6% 27% 31% 12% 1	760
	11th to 20th	Night	22% 4 23% 34% 16% 2	744
	21st to end	Night	21% 7% 21% 36% 14% 2	628
March	1st to 10th	Night	22% 6% 24% 34% 13% 2	760
	11th to 20th	Night	17% 6% 19% 39% 18% 1	760
	21st to end	Night	20% 6% 23% 38% 12% 1	836
April	1st to 10th	Night	18% 7% 21% 36% 17% 2	760
	11th to 20th	Night	15% 7% 27% 36% 14% 1	696
	21st to end	Night	11% 5% 22% 43% 17% 1	570
May	1st to 10th	Night	9% 6% 21% 43% 21%	570
	11th to 20th	Night	10% 5% 17% 35% 30% 2	466
	21st to end	Night	11% 3 17% 38% 28% 3	411
June	1st to 10th	Night	12% 4 12% 43% 25% 3	380
	11th to 20th	Night	11% 3 17% 43% 25% 1	380
	21st to end	Night	4 1 11% 51% 32% 1	380
July	1st to 10th	Night	1 1 14% 47% 34% 2	370
	11th to 20th	Night	2 1 10% 61% 26% 1	368
	21st to end	Night	4 1 7% 52% 34% 1	416
August	1st to 10th	Night	5% 2 9% 50% 32% 2	468
	11th to 20th	Night	1 1 9% 48% 38% 2	564
	21st to end	Night	4 2 12% 46% 33% 3	801
September	1st to 10th	Night	4 1 9% 52% 32% 2	760
	11th to 20th	Night	7% 3 11% 42% 34% 4	760
	21st to end	Night	9% 2 15% 39% 29% 6%	760
October	1st to 10th	Night	10% 2 16% 43% 26% 2	760
	11th to 20th	Night	12% 4 16% 41% 25% 3	760
	21st to end	Night	15% 3 21% 39% 19% 3	836
November	1st to 10th	Night	21% 4 19% 37% 17% 2	754
	11th to 20th	Night	25% 4 18% 35% 16% 1	760
	21st to end	Night	18% 4 21% 37% 16% 4	760
December	1st to 10th	Night	22% 5% 21% 34% 16% 2	760
	11th to 20th	Night	27% 4 19% 34% 14% 2	760
	21st to end	Night	30% 4 23% 31% 10% 2	836

Page generated at 2024-11-01 20:47:53. Version ac07

Copyright © 2024 Attilla Danko.