Sandbank Stream Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sandbank Stream Campground clear sky chart from 2005-11-06 to 2026-04-17.

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	17% 9% 3 7% 5% 5% 5% 4 6% 7% 32%	130949
	Night	16% 9% 3 8% 5% 5% 5% 4 5% 6% 34%	131265
Transparency	Day	50% 6% 12% 20% 11% 1	134436
	Night	50% 6% 12% 20% 11% 1	135867
Seeing	Day	25% 16% 30% 20% 7% 2	17637
	Night	23% 13% 31% 25% 7%	25972

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	11% 14% 5% 10% 5% 4 4 3 4 5% 34%	4431
	11th to 20th	Day	12% 14% 5% 12% 6% 5% 4 4 6% 5% 27%	4650
	21st to end	Day	6% 9% 3 10% 6% 6% 6% 5% 7% 6% 36%	5124
February	1st to 10th	Day	11% 11% 5% 9% 7% 6% 6% 4 6% 6% 29%	1872
	11th to 20th	Day	13% 10% 4 11% 7% 5% 5% 4 5% 6% 30%	1920
	21st to end	Day	12% 11% 4 10% 6% 5% 5% 4 5% 5% 34%	1730
March	1st to 10th	Day	21% 14% 3 9% 5% 5% 3 3 5% 5% 28%	4612
	11th to 20th	Day	17% 16% 4 8% 5% 4 5% 3 4 5% 28%	5090
	21st to end	Day	23% 12% 3 7% 5% 5% 4 3 4 7% 27%	5587
April	1st to 10th	Day	20% 12% 4 8% 5% 4 5% 4 5% 6% 28%	2504
	11th to 20th	Day	20% 10% 3 7% 5% 4 4 3 4 6% 33%	2648
	21st to end	Day	22% 10% 3 7% 4 4 4 3 4 5% 34%	2600
May	1st to 10th	Day	25% 9% 3 8% 5% 5% 5% 4 6% 5% 25%	5886
	11th to 20th	Day	25% 8% 3 7% 4 4 5% 4 6% 7% 28%	5950
	21st to end	Day	19% 8% 2 7% 6% 5% 5% 5% 6% 7% 28%	7406
June	1st to 10th	Day	22% 8% 3 7% 5% 5% 4 4 6% 7% 29%	3000
	11th to 20th	Day	18% 7% 2 6% 5% 5% 4 4 6% 8% 34%	3000
	21st to end	Day	25% 8% 3 6% 6% 4 6% 5% 6% 6% 27%	3000
July	1st to 10th	Day	14% 7% 2 7% 6% 6% 7% 5% 8% 10% 28%	6820
	11th to 20th	Day	16% 7% 2 7% 5% 4 5% 4 5% 8% 37%	6391
	21st to end	Day	13% 6% 2 5% 5% 5% 5% 4 7% 9% 39%	6926
August	1st to 10th	Day	17% 6% 2 7% 5% 5% 6% 5% 7% 8% 33%	4243
	11th to 20th	Day	14% 8% 3 7% 5% 5% 6% 4 6% 8% 33%	4175
	21st to end	Day	15% 6% 2 6% 4 5% 5% 4 6% 8% 40%	4675
September	1st to 10th	Day	13% 5% 2 5% 4 4 5% 3 6% 8% 45%	2333
	11th to 20th	Day	14% 5% 2 6% 4 4 4 4 5% 6% 48%	2200
	21st to end	Day	17% 7% 2 6% 4 3 4 3 5% 7% 42%	2200
October	1st to 10th	Day	17% 7% 2 6% 5% 4 4 3 4 7% 41%	2129
	11th to 20th	Day	20% 9% 3 6% 5% 4 4 3 6% 6% 33%	1965
	21st to end	Day	23% 10% 3 8% 4 4 5% 4 5% 6% 29%	1980
November	1st to 10th	Day	19% 9% 2 7% 6% 5% 4 3 5% 6% 34%	1851
	11th to 20th	Day	18% 9% 2 8% 5% 4 4 3 5% 7% 35%	1764
	21st to end	Day	20% 11% 3 7% 5% 4 4 4 5% 7% 30%	1680
December	1st to 10th	Day	17% 12% 3 9% 5% 5% 4 4 5% 7% 30%	2366
	11th to 20th	Day	19% 9% 3 7% 4 4 4 3 5% 5% 36%	2688
	21st to end	Day	18% 10% 4 8% 4 4 4 3 5% 6% 33%	3553
January	1st to 10th	Night	10% 13% 5% 10% 5% 5% 5% 4 5% 6% 31%	8471
	11th to 20th	Night	12% 13% 5% 11% 7% 7% 7% 5% 6% 7% 22%	8235
	21st to end	Night	7% 9% 4 9% 6% 7% 6% 5% 6% 6% 36%	9057
February	1st to 10th	Night	10% 13% 4 7% 6% 6% 4 5% 5% 6% 32%	2746
	11th to 20th	Night	10% 12% 4 11% 6% 5% 5% 4 6% 6% 31%	2584
	21st to end	Night	14% 10% 3 8% 5% 5% 4 3 5% 6% 37%	2076
March	1st to 10th	Night	22% 11% 3 9% 5% 4 5% 4 5% 5% 28%	5448
	11th to 20th	Night	17% 11% 3 8% 5% 5% 5% 4 6% 7% 28%	5089
	21st to end	Night	25% 11% 3 6% 4 4 4 4 6% 7% 28%	5587
April	1st to 10th	Night	20% 13% 3 7% 5% 5% 4 4 4 6% 31%	2112
	11th to 20th	Night	20% 9% 2 7% 3 4 4 3 5% 6% 37%	1834
	21st to end	Night	22% 10% 3 7% 5% 5% 4 3 5% 5% 32%	1800
May	1st to 10th	Night	24% 10% 3 8% 5% 4 4 4 6% 6% 27%	4054
	11th to 20th	Night	22% 8% 2 8% 5% 5% 5% 4 6% 7% 28%	3972
	21st to end	Night	17% 8% 2 5% 4 4 4 4 5% 8% 38%	3472
June	1st to 10th	Night	22% 8% 2 6% 6% 5% 4 4 5% 7% 31%	1400
	11th to 20th	Night	16% 6% 3 7% 5% 5% 5% 4 6% 8% 36%	1400
	21st to end	Night	25% 7% 2 7% 5% 3 4 3 6% 6% 32%	1400
July	1st to 10th	Night	14% 6% 3 6% 5% 5% 5% 4 6% 8% 38%	3160
	11th to 20th	Night	19% 6% 2 6% 4 4 4 3 5% 7% 40%	3554
	21st to end	Night	12% 6% 2 5% 4 4 4 4 7% 8% 45%	3926
August	1st to 10th	Night	20% 5% 2 7% 6% 5% 5% 4 6% 7% 34%	2873
	11th to 20th	Night	15% 7% 2 7% 4 5% 6% 4 6% 8% 36%	2872
	21st to end	Night	14% 5% 2 7% 4 3 4 3 4 6% 48%	3223
September	1st to 10th	Night	14% 4 2 5% 4 3 4 3 5% 8% 48%	2061
	11th to 20th	Night	13% 6% 2 4 3 3 4 3 5% 7% 50%	2200
	21st to end	Night	17% 7% 3 6% 4 3 3 3 5% 7% 44%	2200
October	1st to 10th	Night	17% 5% 1 6% 4 3 4 3 6% 6% 45%	2270
	11th to 20th	Night	17% 7% 2 7% 5% 4 4 4 5% 7% 38%	2432
	21st to end	Night	23% 8% 3 6% 4 4 4 4 4 6% 34%	2860
November	1st to 10th	Night	19% 7% 2 6% 4 4 5% 4 6% 7% 35%	2667
	11th to 20th	Night	17% 7% 3 8% 5% 4 4 3 6% 6% 37%	2856
	21st to end	Night	18% 10% 3 7% 5% 4 4 4 6% 6% 34%	2940
December	1st to 10th	Night	14% 12% 4 8% 5% 5% 6% 4 5% 7% 31%	5026
	11th to 20th	Night	22% 9% 3 7% 4 4 4 3 4 5% 34%	5741
	21st to end	Night	18% 11% 3 7% 5% 4 4 3 4 5% 34%	7667

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	52% 4 12% 21% 10% 1	4432
	11th to 20th	Day	58% 4 9% 20% 8% 1	4680
	21st to end	Day	46% 6% 9% 17% 19% 2	5124
February	1st to 10th	Day	55% 5% 10% 18% 10% 3	1872
	11th to 20th	Day	55% 5% 10% 17% 12% 1	1928
	21st to end	Day	52% 5% 8% 20% 11% 4	1730
March	1st to 10th	Day	59% 4 8% 9% 15% 4	4615
	11th to 20th	Day	57% 5% 15% 13% 8% 1	5090
	21st to end	Day	59% 3 6% 17% 13% 3	5587
April	1st to 10th	Day	57% 5% 9% 15% 11% 2	2504
	11th to 20th	Day	52% 5% 9% 19% 14% 2	2648
	21st to end	Day	52% 4 9% 19% 12% 4	2600
May	1st to 10th	Day	59% 6% 8% 18% 8% 1	5897
	11th to 20th	Day	55% 6% 12% 18% 6% 3	5954
	21st to end	Day	51% 8% 12% 15% 12% 1	7406
June	1st to 10th	Day	54% 6% 12% 17% 10% 1	3000
	11th to 20th	Day	47% 6% 12% 21% 13% 2	3000
	21st to end	Day	55% 8% 12% 16% 9% 1	3000
July	1st to 10th	Day	48% 8% 18% 18% 8%	6745
	11th to 20th	Day	45% 7% 13% 27% 9%	6315
	21st to end	Day	40% 7% 13% 30% 10%	6728
August	1st to 10th	Day	46% 8% 14% 25% 7%	4229
	11th to 20th	Day	47% 7% 17% 22% 7%	4214
	21st to end	Day	41% 6% 15% 24% 13%	4675
September	1st to 10th	Day	37% 6% 13% 26% 17% 1	2333
	11th to 20th	Day	36% 6% 11% 29% 17% 1	2200
	21st to end	Day	41% 6% 11% 28% 14% 1	2200
October	1st to 10th	Day	52% 5% 11% 23% 9%	3467
	11th to 20th	Day	47% 4 12% 29% 8%	3181
	21st to end	Day	41% 4 17% 21% 17%	3180
November	1st to 10th	Day	52% 5% 12% 19% 11% 1	1851
	11th to 20th	Day	50% 6% 12% 19% 11% 2	1764
	21st to end	Day	54% 5% 15% 19% 6%	1680
December	1st to 10th	Day	54% 5% 17% 13% 11%	2366
	11th to 20th	Day	50% 4 12% 15% 13% 6%	2688
	21st to end	Day	52% 5% 11% 15% 13% 4	3553
January	1st to 10th	Night	55% 6% 12% 17% 10%	8471
	11th to 20th	Night	62% 6% 11% 14% 7% 1	8280
	21st to end	Night	47% 5% 10% 19% 17% 3	9057
February	1st to 10th	Night	52% 5% 10% 20% 11% 2	2746
	11th to 20th	Night	51% 5% 11% 18% 12% 2	2587
	21st to end	Night	49% 4 9% 21% 14% 3	2076
March	1st to 10th	Night	60% 4 7% 14% 12% 3	5458
	11th to 20th	Night	53% 7% 17% 14% 8% 1	5090
	21st to end	Night	56% 4 6% 19% 14% 1	5587
April	1st to 10th	Night	55% 5% 7% 15% 14% 3	2112
	11th to 20th	Night	49% 4 10% 19% 15% 3	1834
	21st to end	Night	54% 5% 9% 17% 13% 3	1800
May	1st to 10th	Night	57% 6% 11% 16% 9% 1	4060
	11th to 20th	Night	53% 9% 11% 20% 6% 1	3973
	21st to end	Night	43% 7% 14% 22% 12% 1	3473
June	1st to 10th	Night	52% 7% 11% 21% 9% 1	1400
	11th to 20th	Night	45% 7% 13% 21% 12% 2	1400
	21st to end	Night	53% 7% 12% 18% 9% 1	1400
July	1st to 10th	Night	43% 7% 18% 23% 9%	3125
	11th to 20th	Night	44% 6% 13% 31% 6%	3508
	21st to end	Night	37% 7% 17% 29% 10%	3809
August	1st to 10th	Night	49% 8% 13% 24% 6%	2863
	11th to 20th	Night	45% 8% 17% 21% 8% 1	2899
	21st to end	Night	39% 5% 14% 24% 17% 1	3223
September	1st to 10th	Night	34% 7% 13% 33% 13% 1	2061
	11th to 20th	Night	34% 6% 11% 32% 16% 1	2200
	21st to end	Night	41% 5% 11% 26% 16% 1	2200
October	1st to 10th	Night	46% 5% 11% 25% 12%	3712
	11th to 20th	Night	42% 5% 12% 30% 12%	3955
	21st to end	Night	42% 4 18% 21% 14% 1	4610
November	1st to 10th	Night	48% 6% 13% 22% 10% 1	2667
	11th to 20th	Night	48% 5% 13% 19% 12% 2	2856
	21st to end	Night	51% 6% 14% 17% 10% 1	2940
December	1st to 10th	Night	53% 5% 12% 21% 8%	5026
	11th to 20th	Night	54% 4 9% 17% 15% 1	5742
	21st to end	Night	53% 4 10% 17% 13% 2	7667

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	25% 25% 30% 18% 3	220
	11th to 20th	Day	32% 22% 31% 11% 4 1	220
	21st to end	Day	19% 21% 38% 15% 6%	242
February	1st to 10th	Day	24% 19% 33% 18% 4 1	412
	11th to 20th	Day	24% 26% 31% 15% 3	467
	21st to end	Day	24% 22% 32% 20% 3	446
March	1st to 10th	Day	30% 21% 31% 15% 3	540
	11th to 20th	Day	29% 22% 29% 14% 5%	540
	21st to end	Day	32% 20% 27% 15% 4 1	594
April	1st to 10th	Day	36% 19% 26% 14% 4 1	540
	11th to 20th	Day	34% 22% 27% 11% 6%	516
	21st to end	Day	34% 20% 29% 12% 4 1	500
May	1st to 10th	Day	32% 18% 30% 16% 3 1	503
	11th to 20th	Day	28% 19% 29% 18% 5% 2	527
	21st to end	Day	24% 19% 30% 20% 5% 1	770
June	1st to 10th	Day	28% 15% 30% 17% 9% 1	730
	11th to 20th	Day	23% 14% 28% 22% 10% 1	730
	21st to end	Day	28% 10% 29% 23% 9% 1	730
July	1st to 10th	Day	17% 12% 34% 25% 10% 2	720
	11th to 20th	Day	20% 8% 39% 20% 11% 2	541
	21st to end	Day	16% 10% 34% 30% 9% 2	576
August	1st to 10th	Day	16% 7% 32% 29% 12% 4	526
	11th to 20th	Day	18% 9% 26% 29% 14% 4	519
	21st to end	Day	17% 12% 27% 28% 12% 3	583
September	1st to 10th	Day	14% 14% 30% 26% 12% 4	530
	11th to 20th	Day	19% 11% 24% 26% 14% 7%	530
	21st to end	Day	20% 13% 31% 21% 10% 5%	530
October	1st to 10th	Day	20% 13% 27% 23% 12% 4	490
	11th to 20th	Day	28% 15% 30% 17% 7% 3	420
	21st to end	Day	30% 18% 27% 21% 5%	462
November	1st to 10th	Day	32% 14% 28% 20% 6%	425
	11th to 20th	Day	27% 17% 33% 16% 6% 1	430
	21st to end	Day	30% 21% 27% 17% 4 1	430
December	1st to 10th	Day	27% 15% 36% 18% 4 1	236
	11th to 20th	Day	32% 23% 30% 11% 4	220
	21st to end	Day	30% 23% 25% 17% 5%	242
January	1st to 10th	Night	21% 19% 33% 22% 4 1	884
	11th to 20th	Night	24% 17% 33% 21% 4	840
	21st to end	Night	15% 19% 38% 23% 5%	924
February	1st to 10th	Night	20% 19% 36% 22% 4	840
	11th to 20th	Night	20% 22% 35% 19% 3	823
	21st to end	Night	23% 16% 33% 25% 3	692
March	1st to 10th	Night	24% 16% 37% 21% 2	840
	11th to 20th	Night	24% 16% 34% 20% 5%	840
	21st to end	Night	24% 16% 34% 20% 6%	924
April	1st to 10th	Night	29% 17% 32% 18% 3	840
	11th to 20th	Night	26% 16% 33% 20% 5%	614
	21st to end	Night	33% 13% 29% 20% 5%	600
May	1st to 10th	Night	26% 13% 33% 24% 4 1	600
	11th to 20th	Night	24% 14% 33% 22% 6%	570
	21st to end	Night	21% 10% 37% 27% 6%	433
June	1st to 10th	Night	24% 9% 30% 30% 7% 1	400
	11th to 20th	Night	18% 10% 29% 34% 10%	400
	21st to end	Night	28% 5% 27% 34% 7%	400
July	1st to 10th	Night	19% 4 33% 34% 10% 1	390
	11th to 20th	Night	18% 5% 28% 37% 12% 1	388
	21st to end	Night	19% 4 26% 39% 12%	438
August	1st to 10th	Night	18% 5% 25% 36% 16%	568
	11th to 20th	Night	16% 4 25% 37% 18% 1	592
	21st to end	Night	15% 7% 27% 35% 15% 2	660
September	1st to 10th	Night	17% 5% 33% 29% 15% 1	771
	11th to 20th	Night	17% 9% 24% 33% 15% 2	800
	21st to end	Night	22% 7% 31% 26% 14% 1	800
October	1st to 10th	Night	22% 10% 27% 29% 12% 1	800
	11th to 20th	Night	24% 11% 29% 25% 11%	800
	21st to end	Night	30% 14% 29% 23% 5%	880
November	1st to 10th	Night	27% 12% 31% 23% 7%	820
	11th to 20th	Night	23% 16% 30% 23% 7% 1	906
	21st to end	Night	27% 18% 27% 23% 5%	950
December	1st to 10th	Night	28% 13% 34% 21% 4 1	950
	11th to 20th	Night	27% 19% 31% 20% 3	950
	21st to end	Night	27% 16% 33% 19% 4	1045

Page generated at 2026-04-14 02:44:28. Version ac07

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