Banjo Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Banjo Creek clear sky chart from 2005-11-06 to 2026-01-17.

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 7% 5% 5% 5% 4 6% 8% 40%	126639
	Night	13% 6% 2 6% 4 4 4 4 6% 7% 43%	125048
Transparency	Day	40% 8% 12% 19% 16% 5%	130239
	Night	38% 7% 12% 19% 18% 5%	129517
Seeing	Day	16% 13% 27% 25% 14% 4	16968
	Night	16% 11% 28% 31% 13% 2	26809

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	13% 5% 2 5% 3 3 3 2 3 4 58%	4146
	11th to 20th	Day	13% 5% 2 5% 3 3 3 3 4 4 55%	4114
	21st to end	Day	11% 12% 3 8% 4 4 4 3 4 4 42%	4466
February	1st to 10th	Day	15% 8% 3 6% 5% 4 4 3 5% 5% 43%	1800
	11th to 20th	Day	20% 6% 2 6% 4 4 3 3 3 5% 43%	1923
	21st to end	Day	13% 7% 3 6% 5% 4 4 3 6% 7% 42%	1650
March	1st to 10th	Day	22% 8% 2 5% 4 4 4 3 5% 5% 38%	4885
	11th to 20th	Day	11% 5% 2 5% 3 3 4 3 5% 6% 53%	4980
	21st to end	Day	12% 5% 2 5% 3 4 4 3 4 5% 51%	5573
April	1st to 10th	Day	11% 6% 2 4 4 3 4 4 4 6% 52%	2400
	11th to 20th	Day	9% 4 2 5% 4 3 4 4 5% 8% 51%	2374
	21st to end	Day	9% 5% 2 6% 5% 4 5% 5% 6% 8% 47%	2400
May	1st to 10th	Day	9% 6% 3 7% 5% 6% 6% 5% 7% 9% 36%	5405
	11th to 20th	Day	17% 8% 3 9% 6% 6% 6% 4 6% 8% 28%	5756
	21st to end	Day	12% 6% 3 6% 5% 5% 5% 4 6% 9% 40%	6834
June	1st to 10th	Day	10% 6% 2 6% 6% 6% 6% 6% 7% 10% 36%	2800
	11th to 20th	Day	8% 5% 2 6% 6% 6% 6% 6% 8% 10% 38%	2800
	21st to end	Day	6% 6% 2 6% 6% 6% 7% 6% 9% 13% 34%	2800
July	1st to 10th	Day	8% 6% 3 8% 7% 7% 8% 6% 9% 12% 26%	6051
	11th to 20th	Day	8% 7% 3 11% 7% 7% 7% 7% 9% 12% 22%	5900
	21st to end	Day	9% 7% 3 9% 6% 7% 8% 6% 8% 11% 26%	6424
August	1st to 10th	Day	20% 11% 4 10% 6% 6% 5% 4 7% 9% 19%	4170
	11th to 20th	Day	10% 7% 2 7% 6% 6% 6% 5% 8% 8% 35%	3850
	21st to end	Day	8% 5% 2 7% 6% 6% 6% 5% 7% 10% 38%	4312
September	1st to 10th	Day	12% 6% 3 7% 5% 6% 5% 4 7% 8% 36%	2400
	11th to 20th	Day	16% 6% 3 7% 5% 5% 6% 4 5% 7% 36%	2400
	21st to end	Day	20% 8% 2 7% 5% 4 3 4 5% 7% 35%	2129
October	1st to 10th	Day	13% 7% 2 6% 5% 4 4 4 5% 6% 45%	2000
	11th to 20th	Day	13% 6% 3 5% 4 4 3 2 4 6% 51%	2000
	21st to end	Day	12% 6% 3 5% 3 3 3 3 4 5% 53%	2200
November	1st to 10th	Day	14% 6% 2 4 4 3 3 3 4 7% 50%	2057
	11th to 20th	Day	14% 6% 2 3 4 3 4 3 5% 5% 51%	1895
	21st to end	Day	12% 5% 2 5% 3 3 3 4 5% 8% 50%	1877
December	1st to 10th	Day	13% 5% 1 5% 4 4 3 3 4 5% 54%	2680
	11th to 20th	Day	14% 8% 3 6% 3 4 4 3 4 6% 44%	3070
	21st to end	Day	12% 6% 2 6% 3 4 4 3 5% 6% 50%	4118
January	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 4 5% 53%	6019
	11th to 20th	Night	13% 5% 2 5% 4 3 3 3 4 5% 51%	5979
	21st to end	Night	12% 9% 3 7% 4 4 4 3 5% 6% 45%	6490
February	1st to 10th	Night	18% 6% 2 5% 4 3 4 4 5% 7% 42%	2600
	11th to 20th	Night	20% 8% 3 6% 3 3 4 3 4 5% 41%	2361
	21st to end	Night	15% 7% 2 5% 3 3 3 4 4 6% 47%	1980
March	1st to 10th	Night	20% 9% 2 6% 4 4 4 3 4 4 40%	4965
	11th to 20th	Night	14% 6% 2 5% 3 3 3 3 5% 6% 51%	4980
	21st to end	Night	14% 5% 2 4 4 4 4 3 4 6% 50%	5358
April	1st to 10th	Night	13% 4 2 6% 4 4 4 3 5% 6% 48%	2000
	11th to 20th	Night	9% 5% 2 5% 4 5% 5% 4 6% 7% 48%	1975
	21st to end	Night	10% 4 1 5% 4 5% 4 3 6% 7% 51%	2000
May	1st to 10th	Night	9% 7% 3 8% 6% 6% 6% 5% 7% 9% 35%	4490
	11th to 20th	Night	18% 8% 2 8% 5% 5% 5% 4 6% 8% 31%	4180
	21st to end	Night	14% 6% 2 8% 5% 4 5% 4 6% 9% 37%	4015
June	1st to 10th	Night	8% 6% 3 7% 5% 4 5% 5% 7% 9% 41%	1600
	11th to 20th	Night	8% 5% 3 6% 5% 5% 5% 5% 8% 11% 40%	1600
	21st to end	Night	7% 6% 2 6% 5% 5% 7% 5% 8% 11% 39%	1600
July	1st to 10th	Night	7% 4 2 7% 5% 5% 6% 5% 9% 15% 35%	3874
	11th to 20th	Night	8% 7% 3 9% 6% 7% 7% 6% 9% 14% 24%	4057
	21st to end	Night	11% 6% 3 7% 5% 5% 6% 6% 9% 10% 31%	4427
August	1st to 10th	Night	16% 10% 4 8% 5% 5% 6% 4 7% 10% 26%	2945
	11th to 20th	Night	9% 7% 3 8% 6% 5% 7% 5% 6% 9% 35%	3197
	21st to end	Night	8% 5% 2 7% 4 5% 6% 6% 9% 9% 40%	3586
September	1st to 10th	Night	10% 5% 2 6% 5% 5% 5% 5% 6% 9% 43%	2000
	11th to 20th	Night	15% 7% 3 6% 5% 4 4 5% 6% 7% 39%	2000
	21st to end	Night	17% 7% 3 8% 5% 5% 4 3 5% 7% 35%	2266
October	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 48%	2400
	11th to 20th	Night	14% 7% 2 5% 3 3 3 3 4 5% 52%	2400
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 55%	2640
November	1st to 10th	Night	14% 6% 2 5% 4 3 4 2 5% 5% 50%	2461
	11th to 20th	Night	15% 7% 3 5% 3 3 3 3 4 5% 48%	2723
	21st to end	Night	11% 5% 2 6% 3 3 3 3 5% 7% 51%	2740
December	1st to 10th	Night	12% 5% 2 5% 3 3 3 2 4 5% 55%	4720
	11th to 20th	Night	16% 6% 3 7% 4 4 4 4 6% 6% 40%	5345
	21st to end	Night	13% 5% 2 4 3 3 4 3 5% 7% 50%	7075

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	32% 3 6% 20% 28% 10%	4147
	11th to 20th	Day	33% 4 5% 17% 32% 9%	4114
	21st to end	Day	45% 5% 6% 16% 19% 8%	4466
February	1st to 10th	Day	42% 5% 11% 22% 18% 3	1800
	11th to 20th	Day	44% 4 8% 16% 21% 5%	1932
	21st to end	Day	40% 7% 9% 18% 20% 6%	1650
March	1st to 10th	Day	47% 5% 8% 15% 17% 9%	4885
	11th to 20th	Day	31% 5% 7% 17% 25% 14%	4980
	21st to end	Day	36% 4 9% 22% 21% 7%	5573
April	1st to 10th	Day	33% 6% 10% 20% 24% 6%	2400
	11th to 20th	Day	31% 7% 12% 22% 21% 7%	2374
	21st to end	Day	34% 8% 14% 23% 19% 3	2400
May	1st to 10th	Day	40% 11% 17% 21% 10% 1	5437
	11th to 20th	Day	50% 9% 14% 18% 9% 1	5760
	21st to end	Day	38% 8% 13% 25% 14% 2	6849
June	1st to 10th	Day	41% 11% 14% 18% 15% 1	2800
	11th to 20th	Day	37% 12% 19% 19% 13% 1	2800
	21st to end	Day	37% 13% 17% 21% 11% 1	2800
July	1st to 10th	Day	45% 13% 19% 17% 6% 1	5986
	11th to 20th	Day	50% 15% 22% 11% 2	5831
	21st to end	Day	48% 11% 15% 19% 7%	6240
August	1st to 10th	Day	60% 11% 16% 10% 3	4157
	11th to 20th	Day	42% 11% 13% 22% 11%	3886
	21st to end	Day	38% 9% 15% 26% 11% 1	4312
September	1st to 10th	Day	43% 10% 16% 15% 13% 3	2400
	11th to 20th	Day	46% 8% 11% 18% 15% 2	2400
	21st to end	Day	48% 8% 11% 18% 14% 2	2129
October	1st to 10th	Day	36% 5% 7% 23% 23% 5%	3260
	11th to 20th	Day	25% 4 5% 18% 26% 22%	3240
	21st to end	Day	26% 4 5% 26% 31% 9%	3538
November	1st to 10th	Day	35% 5% 10% 20% 26% 5%	2057
	11th to 20th	Day	35% 4 8% 21% 24% 7%	1895
	21st to end	Day	33% 5% 10% 24% 23% 5%	1877
December	1st to 10th	Day	34% 5% 7% 23% 24% 7%	2680
	11th to 20th	Day	41% 5% 12% 20% 17% 5%	3066
	21st to end	Day	35% 5% 13% 25% 20% 1	4118
January	1st to 10th	Night	33% 4 7% 18% 31% 8%	6019
	11th to 20th	Night	35% 4 6% 15% 32% 8%	5979
	21st to end	Night	40% 5% 8% 17% 24% 6%	6490
February	1st to 10th	Night	41% 5% 10% 22% 17% 5%	2600
	11th to 20th	Night	45% 5% 10% 15% 19% 6%	2363
	21st to end	Night	38% 5% 9% 20% 20% 8%	1980
March	1st to 10th	Night	46% 6% 8% 14% 19% 8%	4965
	11th to 20th	Night	34% 6% 9% 12% 24% 15%	4980
	21st to end	Night	35% 6% 10% 24% 19% 5%	5358
April	1st to 10th	Night	36% 7% 11% 18% 22% 7%	2000
	11th to 20th	Night	33% 7% 13% 23% 19% 5%	1975
	21st to end	Night	30% 9% 14% 26% 17% 4	2000
May	1st to 10th	Night	41% 12% 18% 20% 9% 1	4520
	11th to 20th	Night	49% 9% 12% 19% 11%	4181
	21st to end	Night	40% 11% 15% 23% 11% 1	4022
June	1st to 10th	Night	36% 10% 18% 22% 13% 1	1600
	11th to 20th	Night	34% 13% 18% 24% 10% 1	1600
	21st to end	Night	36% 12% 19% 23% 11%	1600
July	1st to 10th	Night	35% 12% 27% 19% 6% 1	3831
	11th to 20th	Night	46% 15% 25% 11% 2	4006
	21st to end	Night	44% 12% 16% 20% 7%	4297
August	1st to 10th	Night	52% 10% 21% 14% 2	2934
	11th to 20th	Night	43% 12% 17% 19% 8%	3227
	21st to end	Night	35% 10% 16% 26% 12% 1	3586
September	1st to 10th	Night	36% 11% 17% 19% 15% 2	2000
	11th to 20th	Night	43% 9% 13% 19% 14% 3	2000
	21st to end	Night	46% 7% 13% 20% 12% 1	2266
October	1st to 10th	Night	40% 5% 7% 19% 26% 3	3920
	11th to 20th	Night	25% 3 5% 18% 24% 24%	3899
	21st to end	Night	23% 4 6% 28% 28% 11%	4252
November	1st to 10th	Night	36% 5% 8% 19% 26% 5%	2461
	11th to 20th	Night	38% 5% 8% 17% 25% 8%	2723
	21st to end	Night	33% 5% 9% 24% 22% 6%	2740
December	1st to 10th	Night	32% 4 8% 14% 32% 10%	4720
	11th to 20th	Night	43% 6% 13% 14% 18% 6%	5348
	21st to end	Night	33% 6% 13% 27% 20% 2	7075

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	22% 28% 35% 13% 2	330
	11th to 20th	Day	22% 27% 33% 16% 2	318
	21st to end	Day	24% 25% 35% 12% 3	330
February	1st to 10th	Day	23% 19% 39% 16% 2	300
	11th to 20th	Day	31% 21% 34% 11% 2	471
	21st to end	Day	18% 24% 34% 20% 4 1	414
March	1st to 10th	Day	23% 20% 35% 16% 5% 1	500
	11th to 20th	Day	23% 22% 34% 14% 6% 1	500
	21st to end	Day	21% 19% 38% 15% 6%	550
April	1st to 10th	Day	20% 21% 37% 16% 5% 2	500
	11th to 20th	Day	14% 18% 35% 21% 7% 4	492
	21st to end	Day	12% 15% 33% 27% 11% 2	500
May	1st to 10th	Day	13% 17% 37% 23% 9% 2	503
	11th to 20th	Day	17% 11% 28% 30% 12% 3	527
	21st to end	Day	16% 8% 24% 28% 18% 6%	573
June	1st to 10th	Day	11% 8% 30% 31% 17% 4	530
	11th to 20th	Day	10% 5% 23% 36% 19% 7%	530
	21st to end	Day	6% 5% 20% 38% 25% 6%	530
July	1st to 10th	Day	9% 4 15% 34% 30% 8%	525
	11th to 20th	Day	9% 3 12% 36% 31% 8%	524
	21st to end	Day	9% 3 18% 36% 28% 6%	576
August	1st to 10th	Day	15% 5% 18% 32% 22% 8%	526
	11th to 20th	Day	13% 3 16% 30% 28% 11%	519
	21st to end	Day	11% 4 19% 32% 25% 9%	583
September	1st to 10th	Day	13% 6% 22% 28% 19% 13%	530
	11th to 20th	Day	19% 6% 20% 32% 18% 6%	530
	21st to end	Day	23% 6% 23% 25% 17% 7%	530
October	1st to 10th	Day	17% 8% 23% 27% 18% 7%	530
	11th to 20th	Day	16% 13% 26% 29% 13% 4	530
	21st to end	Day	15% 14% 27% 23% 17% 4	583
November	1st to 10th	Day	16% 14% 30% 27% 10% 3	535
	11th to 20th	Day	20% 14% 32% 24% 9% 2	433
	21st to end	Day	17% 16% 29% 23% 14% 1	417
December	1st to 10th	Day	22% 19% 41% 12% 5%	220
	11th to 20th	Day	20% 20% 32% 19% 7% 2	220
	21st to end	Day	19% 19% 38% 15% 9% 1	259
January	1st to 10th	Night	20% 21% 32% 23% 5%	840
	11th to 20th	Night	19% 18% 30% 28% 5%	825
	21st to end	Night	19% 18% 37% 23% 3	880
February	1st to 10th	Night	21% 17% 34% 25% 4	800
	11th to 20th	Night	25% 23% 34% 17% 2	783
	21st to end	Night	19% 19% 34% 25% 3	660
March	1st to 10th	Night	18% 17% 37% 24% 5%	800
	11th to 20th	Night	21% 16% 37% 21% 5% 1	800
	21st to end	Night	18% 18% 36% 23% 5%	880
April	1st to 10th	Night	15% 18% 39% 23% 5%	800
	11th to 20th	Night	13% 15% 40% 25% 8%	791
	21st to end	Night	10% 13% 39% 32% 6% 1	800
May	1st to 10th	Night	13% 13% 41% 26% 7% 1	800
	11th to 20th	Night	17% 9% 28% 34% 11%	661
	21st to end	Night	11% 4 20% 43% 21% 2	477
June	1st to 10th	Night	10% 3 26% 46% 15% 1	400
	11th to 20th	Night	8% 3 25% 45% 19% 2	400
	21st to end	Night	7% 4 19% 49% 20% 1	400
July	1st to 10th	Night	10% 2 13% 47% 25% 4	505
	11th to 20th	Night	8% 1 11% 45% 27% 8%	582
	21st to end	Night	9% 2 15% 46% 24% 4	657
August	1st to 10th	Night	14% 4 12% 39% 27% 4	614
	11th to 20th	Night	12% 2 13% 39% 28% 5%	790
	21st to end	Night	13% 3 13% 36% 30% 5%	880
September	1st to 10th	Night	12% 2 20% 31% 29% 6%	800
	11th to 20th	Night	16% 3 20% 36% 22% 3	800
	21st to end	Night	21% 5% 19% 32% 21% 2	800
October	1st to 10th	Night	14% 6% 23% 30% 24% 4	800
	11th to 20th	Night	17% 9% 26% 30% 16% 2	800
	21st to end	Night	15% 10% 26% 30% 17% 3	880
November	1st to 10th	Night	16% 10% 25% 34% 15% 1	820
	11th to 20th	Night	19% 13% 30% 27% 10% 1	840
	21st to end	Night	14% 14% 30% 28% 14% 1	840
December	1st to 10th	Night	22% 13% 29% 29% 7%	840
	11th to 20th	Night	17% 12% 33% 30% 7%	840
	21st to end	Night	16% 16% 32% 29% 8%	924

Page generated at 2026-01-14 01:14:26. Version ac07

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