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 2024-01-14.

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	13% 6% 3 5% 5% 3 5% 5% 6% 8% 41%	74640
	Night	13% 6% 2 5% 5% 3 4 5% 6% 7% 44%	75117
Transparency	Day	26% 39% 8% 13% 12% 2	74361
	Night	25% 38% 8% 13% 13% 3	74915
Seeing	Day	16% 12% 27% 26% 15% 5%	14282
	Night	16% 11% 28% 31% 14% 2	24138

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	14% 6% 3 5% 4 2 5% 4 4 5% 50%	1706
	11th to 20th	Day	16% 6% 3 4 4 3 4 5% 5% 5% 45%	1647
	21st to end	Day	16% 7% 3 5% 4 2 5% 4 5% 5% 46%	1782
February	1st to 10th	Day	15% 8% 3 5% 5% 3 4 4 5% 6% 42%	1620
	11th to 20th	Day	20% 5% 2 5% 5% 2 4 4 3 6% 45%	1726
	21st to end	Day	14% 7% 4 6% 5% 3 4 4 5% 7% 41%	1480
March	1st to 10th	Day	14% 6% 2 4 3 2 4 3 4 5% 53%	1956
	11th to 20th	Day	17% 6% 3 5% 4 3 4 4 5% 7% 42%	1980
	21st to end	Day	15% 6% 3 5% 5% 3 5% 4 5% 6% 43%	2217
April	1st to 10th	Day	12% 5% 2 3 4 2 4 4 4 6% 53%	2160
	11th to 20th	Day	10% 4 2 4 5% 3 4 5% 5% 9% 50%	2134
	21st to end	Day	10% 5% 2 5% 5% 3 5% 6% 6% 8% 46%	2160
May	1st to 10th	Day	10% 5% 3 5% 6% 4 5% 6% 7% 8% 41%	2160
	11th to 20th	Day	14% 6% 3 7% 6% 4 5% 5% 6% 8% 35%	2252
	21st to end	Day	10% 6% 3 6% 6% 4 6% 5% 7% 10% 38%	2681
June	1st to 10th	Day	10% 5% 3 5% 7% 4 7% 6% 7% 11% 35%	2520
	11th to 20th	Day	9% 4 2 5% 6% 4 6% 7% 8% 10% 37%	2520
	21st to end	Day	6% 6% 3 5% 7% 4 8% 8% 9% 13% 33%	2520
July	1st to 10th	Day	9% 5% 3 6% 7% 4 6% 7% 8% 12% 33%	2407
	11th to 20th	Day	9% 5% 4 8% 7% 4 6% 8% 9% 11% 30%	2340
	21st to end	Day	8% 5% 3 7% 6% 5% 9% 7% 8% 12% 30%	2547
August	1st to 10th	Day	11% 7% 3 7% 7% 4 6% 6% 8% 11% 30%	2292
	11th to 20th	Day	11% 7% 2 6% 7% 5% 7% 7% 9% 10% 31%	2126
	21st to end	Day	12% 6% 3 6% 8% 5% 6% 6% 7% 9% 32%	2376
September	1st to 10th	Day	12% 6% 3 6% 6% 5% 5% 5% 7% 9% 36%	2160
	11th to 20th	Day	15% 5% 3 5% 6% 4 6% 6% 5% 8% 37%	2160
	21st to end	Day	20% 8% 2 6% 6% 3 4 5% 5% 7% 36%	1918
October	1st to 10th	Day	14% 7% 2 6% 5% 3 4 5% 4 6% 44%	1800
	11th to 20th	Day	12% 5% 3 4 5% 2 4 3 4 7% 50%	1800
	21st to end	Day	12% 6% 3 5% 4 2 3 4 4 5% 52%	1980
November	1st to 10th	Day	15% 5% 2 4 4 3 3 3 4 7% 49%	1857
	11th to 20th	Day	15% 5% 2 3 4 3 4 3 4 5% 51%	1715
	21st to end	Day	14% 4 2 4 3 2 3 5% 5% 8% 50%	1699
December	1st to 10th	Day	17% 6% 2 5% 6% 4 4 4 5% 7% 40%	1520
	11th to 20th	Day	16% 6% 2 4 3 2 3 3 4 5% 53%	1910
	21st to end	Day	14% 7% 3 5% 4 3 4 4 5% 6% 46%	2812
January	1st to 10th	Night	14% 7% 3 4 5% 2 4 4 4 6% 46%	2459
	11th to 20th	Night	14% 7% 3 5% 6% 3 4 4 6% 6% 42%	2391
	21st to end	Night	16% 6% 3 5% 4 2 4 4 5% 5% 47%	2574
February	1st to 10th	Night	19% 6% 3 4 4 2 4 4 5% 8% 42%	2340
	11th to 20th	Night	19% 8% 2 5% 4 2 4 3 4 6% 42%	2119
	21st to end	Night	16% 6% 2 5% 4 3 3 5% 4 6% 46%	1776
March	1st to 10th	Night	14% 4 2 4 4 2 4 3 4 5% 54%	2001
	11th to 20th	Night	15% 8% 2 5% 5% 2 4 4 6% 8% 40%	1980
	21st to end	Night	15% 5% 2 5% 5% 3 4 5% 4 7% 45%	2138
April	1st to 10th	Night	13% 4 2 5% 5% 2 4 4 5% 6% 49%	1800
	11th to 20th	Night	10% 5% 2 5% 4 3 5% 5% 6% 7% 48%	1775
	21st to end	Night	10% 4 2 5% 4 4 4 4 6% 7% 51%	1800
May	1st to 10th	Night	11% 5% 3 4 5% 3 5% 6% 6% 8% 43%	1800
	11th to 20th	Night	14% 6% 2 6% 5% 4 4 4 5% 10% 40%	1656
	21st to end	Night	9% 5% 2 5% 5% 3 5% 5% 7% 10% 43%	1589
June	1st to 10th	Night	8% 5% 3 6% 6% 2 5% 6% 7% 9% 42%	1440
	11th to 20th	Night	8% 5% 3 5% 6% 3 6% 6% 9% 12% 39%	1440
	21st to end	Night	8% 5% 3 5% 6% 4 6% 7% 8% 11% 37%	1440
July	1st to 10th	Night	9% 4 2 6% 7% 4 5% 6% 9% 12% 36%	1548
	11th to 20th	Night	7% 4 2 5% 5% 4 5% 6% 9% 13% 40%	1620
	21st to end	Night	7% 5% 3 6% 6% 4 5% 6% 8% 11% 37%	1771
August	1st to 10th	Night	9% 5% 2 6% 6% 4 6% 7% 7% 11% 37%	1626
	11th to 20th	Night	8% 7% 3 7% 7% 3 6% 7% 7% 11% 34%	1774
	21st to end	Night	12% 5% 2 7% 5% 3 6% 7% 8% 10% 35%	1980
September	1st to 10th	Night	10% 4 2 5% 6% 3 5% 6% 6% 9% 43%	1800
	11th to 20th	Night	14% 6% 3 5% 5% 3 4 6% 6% 7% 41%	1800
	21st to end	Night	18% 7% 3 7% 6% 4 5% 4 5% 7% 36%	2038
October	1st to 10th	Night	13% 5% 2 4 5% 3 4 4 5% 6% 49%	2160
	11th to 20th	Night	13% 6% 2 4 4 3 3 3 4 5% 51%	2160
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 54%	2376
November	1st to 10th	Night	14% 6% 2 5% 4 3 4 3 5% 5% 49%	2221
	11th to 20th	Night	16% 6% 3 5% 4 2 3 4 4 6% 48%	2463
	21st to end	Night	12% 5% 2 5% 4 2 3 4 5% 7% 51%	2478
December	1st to 10th	Night	16% 7% 2 6% 5% 3 5% 4 5% 6% 41%	2660
	11th to 20th	Night	17% 5% 3 5% 4 2 3 4 5% 5% 47%	3285
	21st to end	Night	15% 5% 2 4 4 2 4 4 5% 7% 46%	4839

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	21% 40% 7% 15% 14% 2	1707
	11th to 20th	Day	24% 41% 5% 14% 14% 1	1647
	21st to end	Day	29% 37% 4 12% 14% 4	1782
February	1st to 10th	Day	27% 37% 7% 15% 12% 3	1620
	11th to 20th	Day	27% 37% 4 11% 16% 4	1735
	21st to end	Day	28% 37% 7% 12% 12% 4	1480
March	1st to 10th	Day	21% 36% 7% 16% 16% 4	1956
	11th to 20th	Day	27% 38% 8% 14% 10% 3	1980
	21st to end	Day	30% 37% 7% 12% 11% 2	2217
April	1st to 10th	Day	21% 37% 6% 14% 17% 5%	2160
	11th to 20th	Day	19% 37% 9% 13% 17% 5%	2134
	21st to end	Day	23% 38% 9% 14% 13% 3	2160
May	1st to 10th	Day	26% 39% 10% 15% 10% 1	2160
	11th to 20th	Day	33% 39% 7% 12% 8% 1	2256
	21st to end	Day	26% 42% 10% 15% 7% 1	2681
June	1st to 10th	Day	28% 41% 9% 14% 8%	2520
	11th to 20th	Day	27% 40% 11% 13% 8%	2520
	21st to end	Day	27% 41% 11% 13% 8% 1	2520
July	1st to 10th	Day	26% 42% 10% 13% 8% 1	2342
	11th to 20th	Day	27% 42% 13% 11% 6% 1	2271
	21st to end	Day	27% 43% 13% 14% 2	2405
August	1st to 10th	Day	26% 42% 14% 13% 5%	2279
	11th to 20th	Day	28% 41% 11% 13% 6% 1	2126
	21st to end	Day	33% 41% 9% 12% 5% 1	2376
September	1st to 10th	Day	28% 39% 10% 11% 10% 3	2160
	11th to 20th	Day	26% 39% 8% 12% 13% 1	2160
	21st to end	Day	32% 37% 5% 11% 12% 3	1918
October	1st to 10th	Day	26% 36% 6% 11% 20% 2	1800
	11th to 20th	Day	26% 37% 5% 12% 15% 5%	1800
	21st to end	Day	24% 37% 5% 13% 17% 4	1980
November	1st to 10th	Day	20% 40% 7% 12% 17% 4	1857
	11th to 20th	Day	23% 39% 6% 14% 15% 3	1715
	21st to end	Day	23% 39% 5% 15% 14% 3	1699
December	1st to 10th	Day	24% 41% 7% 15% 10% 2	1520
	11th to 20th	Day	26% 32% 5% 16% 15% 6%	1906
	21st to end	Day	28% 26% 8% 17% 20% 1	2812
January	1st to 10th	Night	24% 40% 6% 13% 15% 2	2459
	11th to 20th	Night	26% 42% 6% 13% 10% 3	2391
	21st to end	Night	27% 37% 5% 14% 13% 4	2574
February	1st to 10th	Night	28% 36% 5% 13% 14% 4	2340
	11th to 20th	Night	28% 37% 6% 11% 14% 5%	2121
	21st to end	Night	27% 36% 6% 13% 13% 5%	1776
March	1st to 10th	Night	20% 36% 7% 16% 15% 5%	2001
	11th to 20th	Night	29% 38% 8% 11% 11% 3	1980
	21st to end	Night	26% 37% 9% 15% 11% 2	2138
April	1st to 10th	Night	24% 37% 6% 12% 16% 5%	1800
	11th to 20th	Night	21% 37% 8% 14% 17% 4	1775
	21st to end	Night	21% 37% 9% 16% 13% 3	1800
May	1st to 10th	Night	24% 39% 10% 16% 10% 1	1800
	11th to 20th	Night	30% 40% 10% 10% 11% 1	1657
	21st to end	Night	23% 42% 11% 16% 7% 1	1590
June	1st to 10th	Night	24% 39% 11% 17% 8%	1440
	11th to 20th	Night	26% 40% 12% 15% 6% 1	1440
	21st to end	Night	27% 41% 12% 13% 7%	1440
July	1st to 10th	Night	25% 42% 11% 14% 8% 1	1503
	11th to 20th	Night	20% 43% 17% 14% 6%	1566
	21st to end	Night	24% 42% 16% 16% 2	1672
August	1st to 10th	Night	22% 42% 17% 16% 3	1615
	11th to 20th	Night	29% 40% 12% 13% 6% 1	1774
	21st to end	Night	29% 41% 12% 13% 4 1	1980
September	1st to 10th	Night	24% 40% 10% 12% 12% 2	1800
	11th to 20th	Night	26% 38% 9% 13% 12% 2	1800
	21st to end	Night	31% 37% 6% 13% 11% 2	2038
October	1st to 10th	Night	23% 38% 5% 11% 20% 3	2160
	11th to 20th	Night	27% 37% 5% 13% 15% 4	2160
	21st to end	Night	22% 37% 5% 13% 18% 5%	2376
November	1st to 10th	Night	19% 41% 4 13% 18% 4	2221
	11th to 20th	Night	25% 40% 5% 11% 16% 3	2463
	21st to end	Night	23% 40% 5% 12% 16% 4	2478
December	1st to 10th	Night	24% 40% 8% 11% 13% 3	2660
	11th to 20th	Night	29% 33% 7% 10% 18% 4	3288
	21st to end	Night	26% 26% 6% 19% 21% 2	4839

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	21% 26% 36% 14% 2	270
	11th to 20th	Day	22% 25% 33% 18% 2	249
	21st to end	Day	23% 25% 33% 14% 4	264
February	1st to 10th	Day	25% 19% 39% 15% 3	240
	11th to 20th	Day	30% 20% 34% 13% 2	394
	21st to end	Day	19% 25% 34% 17% 3 1	346
March	1st to 10th	Day	20% 20% 37% 17% 5% 1	420
	11th to 20th	Day	24% 22% 33% 14% 6% 1	420
	21st to end	Day	22% 20% 34% 17% 7%	462
April	1st to 10th	Day	20% 20% 35% 17% 5% 2	420
	11th to 20th	Day	14% 18% 33% 22% 8% 5%	412
	21st to end	Day	13% 15% 33% 26% 11% 2	420
May	1st to 10th	Day	14% 18% 36% 22% 9% 2	423
	11th to 20th	Day	17% 8% 27% 31% 14% 3	447
	21st to end	Day	15% 6% 24% 30% 19% 6%	485
June	1st to 10th	Day	11% 7% 29% 31% 18% 4	450
	11th to 20th	Day	11% 5% 22% 34% 20% 8%	450
	21st to end	Day	7% 5% 21% 37% 23% 6%	450
July	1st to 10th	Day	9% 3 15% 34% 30% 9%	445
	11th to 20th	Day	9% 3 13% 36% 31% 8%	444
	21st to end	Day	8% 2 19% 37% 28% 5%	488
August	1st to 10th	Day	11% 5% 18% 33% 24% 9%	446
	11th to 20th	Day	13% 2 14% 30% 30% 12%	439
	21st to end	Day	12% 4 15% 32% 27% 10%	495
September	1st to 10th	Day	12% 4 20% 28% 21% 15%	450
	11th to 20th	Day	16% 4 20% 34% 19% 7%	450
	21st to end	Day	23% 6% 22% 25% 17% 8%	450
October	1st to 10th	Day	17% 7% 22% 26% 19% 8%	450
	11th to 20th	Day	14% 12% 27% 29% 14% 4	450
	21st to end	Day	14% 13% 28% 24% 17% 4	495
November	1st to 10th	Day	17% 14% 27% 27% 11% 3	455
	11th to 20th	Day	20% 14% 32% 23% 9% 2	373
	21st to end	Day	18% 13% 27% 24% 16% 1	359
December	1st to 10th	Day	22% 18% 41% 13% 6% 1	180
	11th to 20th	Day	20% 22% 30% 18% 8% 2	180
	21st to end	Day	19% 17% 35% 17% 11% 1	211
January	1st to 10th	Night	20% 20% 31% 23% 5%	760
	11th to 20th	Night	19% 16% 29% 29% 6%	736
	21st to end	Night	19% 18% 36% 23% 4	792
February	1st to 10th	Night	22% 16% 33% 25% 4	720
	11th to 20th	Night	24% 22% 34% 17% 2	703
	21st to end	Night	20% 19% 34% 24% 3	592
March	1st to 10th	Night	17% 16% 37% 24% 6%	720
	11th to 20th	Night	21% 16% 36% 21% 5% 1	720
	21st to end	Night	18% 18% 34% 24% 6%	792
April	1st to 10th	Night	15% 17% 39% 24% 5%	720
	11th to 20th	Night	13% 15% 38% 25% 8%	711
	21st to end	Night	11% 13% 38% 32% 5% 1	720
May	1st to 10th	Night	14% 13% 41% 25% 7% 1	720
	11th to 20th	Night	17% 8% 28% 34% 12%	595
	21st to end	Night	10% 4 18% 45% 22% 1	429
June	1st to 10th	Night	10% 3 27% 44% 15% 1	360
	11th to 20th	Night	7% 3 25% 45% 18% 2	360
	21st to end	Night	8% 4 20% 50% 18% 1	360
July	1st to 10th	Night	9% 2 12% 47% 26% 4	453
	11th to 20th	Night	7% 1 12% 45% 28% 7%	522
	21st to end	Night	9% 2 16% 47% 25% 2	591
August	1st to 10th	Night	12% 3 11% 41% 29% 5%	552
	11th to 20th	Night	11% 2 14% 39% 29% 5%	710
	21st to end	Night	14% 2 13% 34% 32% 5%	792
September	1st to 10th	Night	11% 2 18% 32% 31% 6%	720
	11th to 20th	Night	14% 3 19% 37% 23% 4	720
	21st to end	Night	22% 5% 18% 31% 22% 3	720
October	1st to 10th	Night	14% 6% 23% 29% 24% 4	720
	11th to 20th	Night	16% 10% 24% 30% 17% 2	720
	21st to end	Night	15% 9% 27% 30% 16% 3	792
November	1st to 10th	Night	16% 10% 24% 33% 15% 1	740
	11th to 20th	Night	19% 12% 30% 27% 11% 1	760
	21st to end	Night	14% 14% 30% 27% 15% 1	760
December	1st to 10th	Night	21% 13% 29% 28% 8%	760
	11th to 20th	Night	17% 12% 34% 29% 7% 1	760
	21st to end	Night	16% 16% 31% 28% 8%	836

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