Diascund Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Diascund Creek clear sky chart from 2005-11-06 to 2026-10-29.

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% 2 6% 4 4 4 4 6% 8% 42%	149009
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 44%	143037
Transparency	Day	38% 6% 13% 22% 17% 4	152604
	Night	39% 6% 11% 22% 18% 5%	147513
Seeing	Day	17% 12% 28% 25% 14% 5%	17800
	Night	17% 10% 29% 30% 13% 1	27365

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% 4 1 5% 3 3 3 3 5% 6% 53%	5021
	11th to 20th	Day	13% 6% 2 4 3 3 3 3 4 4 55%	5280
	21st to end	Day	14% 7% 3 6% 4 4 5% 3 4 5% 44%	5780
February	1st to 10th	Day	13% 8% 2 4 5% 4 5% 3 6% 8% 40%	1890
	11th to 20th	Day	21% 7% 2 4 4 3 3 3 4 6% 43%	1958
	21st to end	Day	17% 8% 3 7% 4 5% 5% 4 4 6% 38%	1730
March	1st to 10th	Day	19% 7% 2 7% 4 4 4 3 5% 6% 39%	4954
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 7% 52%	5090
	21st to end	Day	16% 6% 2 6% 4 4 4 3 5% 6% 45%	5696
April	1st to 10th	Day	12% 5% 1 5% 4 3 4 3 5% 7% 50%	2520
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 6% 49%	2494
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 7% 44%	2520
May	1st to 10th	Day	14% 7% 2 7% 4 5% 4 4 6% 9% 38%	7196
	11th to 20th	Day	15% 6% 2 6% 4 4 4 4 5% 8% 40%	7821
	21st to end	Day	19% 7% 2 5% 4 4 4 3 5% 8% 38%	9045
June	1st to 10th	Day	10% 4 2 5% 5% 5% 5% 4 6% 9% 44%	2940
	11th to 20th	Day	11% 6% 2 5% 5% 5% 5% 5% 6% 9% 42%	2940
	21st to end	Day	7% 4 2 6% 5% 6% 5% 5% 8% 11% 40%	2940
July	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 5% 8% 12% 39%	8280
	11th to 20th	Day	12% 8% 3 8% 5% 6% 6% 5% 8% 12% 28%	7745
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 8% 11% 34%	8340
August	1st to 10th	Day	13% 8% 3 8% 5% 6% 6% 6% 8% 13% 25%	6014
	11th to 20th	Day	9% 5% 3 8% 6% 6% 6% 5% 8% 11% 34%	5557
	21st to end	Day	8% 6% 3 7% 4 4 4 4 6% 11% 45%	6080
September	1st to 10th	Day	13% 4 2 6% 4 4 5% 4 5% 8% 44%	2520
	11th to 20th	Day	13% 6% 3 6% 5% 5% 5% 4 6% 7% 41%	2520
	21st to end	Day	20% 9% 2 8% 5% 5% 4 3 5% 5% 34%	2222
October	1st to 10th	Day	15% 6% 2 7% 4 4 4 3 4 6% 46%	2100
	11th to 20th	Day	15% 6% 2 4 3 3 3 3 4 5% 52%	2100
	21st to end	Day	11% 6% 1 5% 4 3 3 3 4 5% 55%	2280
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 4 5% 53%	1989
	11th to 20th	Day	13% 7% 2 5% 3 3 3 3 4 6% 51%	1890
	21st to end	Day	13% 4 1 6% 3 3 3 3 5% 6% 52%	1759
December	1st to 10th	Day	11% 5% 1 6% 4 3 3 3 4 6% 53%	2680
	11th to 20th	Day	19% 7% 2 5% 4 3 3 2 4 5% 47%	3070
	21st to end	Day	13% 5% 2 6% 4 4 4 3 5% 8% 48%	4048
January	1st to 10th	Night	12% 6% 2 5% 4 3 4 3 5% 6% 50%	7855
	11th to 20th	Night	13% 6% 2 5% 4 3 3 2 4 4 54%	7680
	21st to end	Night	16% 6% 2 5% 3 3 3 3 4 5% 49%	8401
February	1st to 10th	Night	16% 8% 2 5% 4 4 4 3 5% 6% 43%	2730
	11th to 20th	Night	21% 7% 1 5% 3 3 4 3 4 5% 42%	2545
	21st to end	Night	17% 7% 2 6% 3 2 3 3 4 5% 46%	2076
March	1st to 10th	Night	19% 7% 2 5% 4 3 3 3 5% 6% 44%	5102
	11th to 20th	Night	13% 5% 3 4 4 3 4 3 5% 6% 50%	5090
	21st to end	Night	14% 7% 2 5% 3 4 3 3 5% 6% 47%	5477
April	1st to 10th	Night	14% 7% 2 6% 4 4 4 3 5% 7% 44%	2100
	11th to 20th	Night	12% 5% 2 5% 4 3 4 4 4 8% 50%	2075
	21st to end	Night	13% 6% 2 5% 4 3 4 4 6% 8% 45%	2100
May	1st to 10th	Night	13% 7% 2 7% 5% 5% 5% 5% 7% 10% 35%	5699
	11th to 20th	Night	16% 7% 2 5% 4 4 4 3 6% 7% 41%	5037
	21st to end	Night	21% 8% 3 6% 4 4 3 3 5% 7% 35%	5108
June	1st to 10th	Night	10% 5% 2 7% 4 6% 5% 5% 7% 10% 40%	1680
	11th to 20th	Night	10% 5% 2 7% 5% 5% 5% 5% 6% 10% 40%	1680
	21st to end	Night	8% 5% 2 7% 6% 4 5% 4 7% 10% 42%	1680
July	1st to 10th	Night	10% 5% 2 7% 5% 6% 6% 5% 7% 9% 38%	4678
	11th to 20th	Night	11% 8% 3 8% 5% 6% 6% 5% 8% 11% 28%	5193
	21st to end	Night	13% 8% 3 8% 6% 5% 6% 5% 7% 8% 31%	5736
August	1st to 10th	Night	16% 9% 3 7% 5% 4 5% 5% 8% 10% 28%	4135
	11th to 20th	Night	8% 7% 3 8% 5% 5% 5% 4 7% 10% 38%	4440
	21st to end	Night	9% 6% 2 6% 4 4 5% 4 6% 9% 44%	5045
September	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 6% 7% 46%	2100
	11th to 20th	Night	12% 6% 2 6% 3 5% 5% 4 6% 7% 44%	2100
	21st to end	Night	21% 9% 3 7% 4 4 4 3 5% 6% 34%	2391
October	1st to 10th	Night	15% 6% 2 6% 4 3 4 3 5% 6% 48%	2520
	11th to 20th	Night	15% 6% 2 5% 4 2 3 2 3 6% 50%	2520
	21st to end	Night	14% 4 1 5% 3 3 3 2 4 5% 55%	2737
November	1st to 10th	Night	13% 6% 2 5% 3 3 4 3 4 5% 51%	2526
	11th to 20th	Night	15% 6% 2 5% 3 3 4 3 5% 5% 48%	2730
	21st to end	Night	12% 5% 2 5% 4 3 4 4 5% 6% 51%	2856
December	1st to 10th	Night	11% 5% 2 4 3 3 4 3 5% 7% 54%	4720
	11th to 20th	Night	18% 7% 3 7% 4 4 4 3 5% 5% 40%	5345
	21st to end	Night	13% 7% 3 6% 3 3 3 3 5% 7% 47%	7150

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	33% 3 10% 25% 21% 8%	5022
	11th to 20th	Day	33% 2 6% 17% 30% 11%	5280
	21st to end	Day	42% 3 7% 26% 18% 3	5780
February	1st to 10th	Day	41% 5% 11% 25% 15% 3	1890
	11th to 20th	Day	43% 4 7% 21% 20% 5%	1967
	21st to end	Day	46% 5% 10% 17% 16% 5%	1730
March	1st to 10th	Day	45% 4 8% 16% 20% 7%	4954
	11th to 20th	Day	32% 4 10% 23% 23% 9%	5090
	21st to end	Day	41% 5% 12% 17% 20% 6%	5696
April	1st to 10th	Day	34% 4 12% 22% 21% 7%	2520
	11th to 20th	Day	35% 4 11% 24% 21% 5%	2494
	21st to end	Day	39% 6% 12% 22% 16% 5%	2520
May	1st to 10th	Day	42% 7% 13% 20% 16% 1	7228
	11th to 20th	Day	41% 6% 13% 24% 15% 1	7825
	21st to end	Day	43% 7% 12% 20% 16% 3	9061
June	1st to 10th	Day	35% 9% 14% 24% 16% 2	2940
	11th to 20th	Day	36% 9% 16% 24% 15% 1	2940
	21st to end	Day	34% 10% 15% 24% 16% 2	2940
July	1st to 10th	Day	35% 9% 19% 23% 10% 2	8210
	11th to 20th	Day	46% 10% 20% 17% 6% 1	7674
	21st to end	Day	41% 9% 14% 19% 17%	8156
August	1st to 10th	Day	48% 11% 20% 17% 4	6001
	11th to 20th	Day	40% 9% 19% 21% 10%	5594
	21st to end	Day	34% 6% 16% 26% 17% 1	6080
September	1st to 10th	Day	37% 8% 13% 19% 19% 4	2520
	11th to 20th	Day	40% 6% 11% 22% 18% 3	2520
	21st to end	Day	51% 5% 9% 18% 14% 3	2222
October	1st to 10th	Day	36% 5% 8% 19% 26% 5%	3360
	11th to 20th	Day	25% 3 6% 20% 37% 10%	3340
	21st to end	Day	22% 3 9% 26% 27% 13%	3618
November	1st to 10th	Day	34% 4 9% 27% 23% 4	1989
	11th to 20th	Day	35% 4 10% 21% 23% 6%	1890
	21st to end	Day	34% 4 9% 27% 22% 5%	1759
December	1st to 10th	Day	33% 3 8% 28% 21% 6%	2680
	11th to 20th	Day	42% 3 12% 21% 17% 5%	3066
	21st to end	Day	36% 4 12% 29% 17% 2	4048
January	1st to 10th	Night	36% 3 11% 22% 21% 8%	7856
	11th to 20th	Night	35% 3 5% 22% 28% 8%	7680
	21st to end	Night	39% 3 6% 27% 21% 5%	8401
February	1st to 10th	Night	42% 5% 10% 22% 18% 4	2730
	11th to 20th	Night	45% 3 7% 21% 18% 5%	2547
	21st to end	Night	41% 4 8% 21% 19% 7%	2076
March	1st to 10th	Night	42% 4 8% 19% 20% 7%	5102
	11th to 20th	Night	35% 4 8% 20% 23% 10%	5090
	21st to end	Night	38% 4 9% 24% 18% 6%	5477
April	1st to 10th	Night	38% 6% 11% 18% 21% 6%	2100
	11th to 20th	Night	34% 5% 12% 23% 21% 6%	2075
	21st to end	Night	36% 6% 12% 24% 18% 4	2100
May	1st to 10th	Night	43% 7% 15% 23% 11% 1	5729
	11th to 20th	Night	41% 6% 12% 26% 14% 1	5038
	21st to end	Night	47% 7% 11% 19% 14% 2	5115
June	1st to 10th	Night	36% 10% 14% 21% 17% 1	1680
	11th to 20th	Night	38% 9% 15% 22% 14% 1	1680
	21st to end	Night	36% 9% 12% 23% 16% 3	1680
July	1st to 10th	Night	40% 11% 14% 22% 11% 2	4640
	11th to 20th	Night	47% 12% 18% 17% 6% 1	5144
	21st to end	Night	47% 8% 11% 19% 14%	5606
August	1st to 10th	Night	49% 10% 19% 17% 4	4124
	11th to 20th	Night	39% 9% 20% 23% 9%	4469
	21st to end	Night	35% 7% 13% 23% 20% 1	5045
September	1st to 10th	Night	35% 9% 15% 19% 17% 4	2100
	11th to 20th	Night	37% 8% 10% 21% 21% 2	2100
	21st to end	Night	50% 7% 10% 15% 15% 3	2391
October	1st to 10th	Night	36% 5% 11% 20% 23% 4	4040
	11th to 20th	Night	26% 3 7% 21% 30% 13%	4019
	21st to end	Night	21% 3 6% 31% 27% 13%	4349
November	1st to 10th	Night	36% 4 9% 23% 23% 4	2526
	11th to 20th	Night	38% 4 8% 20% 21% 9%	2730
	21st to end	Night	34% 5% 8% 25% 23% 5%	2856
December	1st to 10th	Night	32% 4 8% 26% 25% 5%	4720
	11th to 20th	Night	46% 5% 10% 18% 15% 6%	5348
	21st to end	Night	37% 4 12% 29% 17% 2	7150

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% 26% 35% 14% 3	286
	11th to 20th	Day	24% 29% 35% 12% 1	330
	21st to end	Day	19% 25% 40% 13% 2	363
February	1st to 10th	Day	20% 24% 39% 13% 3	330
	11th to 20th	Day	32% 25% 31% 10% 1	446
	21st to end	Day	26% 20% 34% 16% 4	446
March	1st to 10th	Day	22% 21% 36% 16% 5%	540
	11th to 20th	Day	23% 23% 32% 16% 4 1	540
	21st to end	Day	21% 19% 38% 18% 4 1	594
April	1st to 10th	Day	20% 20% 36% 15% 7% 1	540
	11th to 20th	Day	15% 14% 38% 21% 9% 3	532
	21st to end	Day	16% 14% 36% 25% 7% 2	540
May	1st to 10th	Day	17% 16% 36% 21% 8% 2	543
	11th to 20th	Day	21% 9% 30% 25% 12% 2	567
	21st to end	Day	21% 6% 26% 25% 18% 5%	617
June	1st to 10th	Day	11% 6% 29% 29% 22% 4	570
	11th to 20th	Day	13% 7% 22% 33% 20% 5%	570
	21st to end	Day	10% 4 21% 37% 24% 5%	570
July	1st to 10th	Day	9% 3 15% 34% 29% 10%	565
	11th to 20th	Day	8% 2 16% 34% 30% 10%	564
	21st to end	Day	10% 3 18% 33% 27% 9%	620
August	1st to 10th	Day	15% 4 18% 34% 21% 8%	566
	11th to 20th	Day	12% 3 17% 34% 26% 9%	559
	21st to end	Day	8% 2 22% 30% 25% 13%	627
September	1st to 10th	Day	14% 3 19% 28% 22% 13%	570
	11th to 20th	Day	16% 5% 18% 31% 19% 11%	570
	21st to end	Day	26% 9% 25% 21% 14% 4	570
October	1st to 10th	Day	18% 6% 21% 30% 15% 9%	570
	11th to 20th	Day	17% 12% 25% 29% 14% 3	570
	21st to end	Day	15% 13% 30% 26% 11% 5%	615
November	1st to 10th	Day	16% 10% 32% 26% 13% 3	499
	11th to 20th	Day	20% 16% 31% 24% 8% 1	430
	21st to end	Day	19% 18% 30% 21% 10% 1	299
December	1st to 10th	Day	23% 18% 38% 15% 5% 1	220
	11th to 20th	Day	22% 15% 34% 20% 8%	220
	21st to end	Day	23% 17% 32% 19% 8% 1	242
January	1st to 10th	Night	19% 20% 36% 22% 3	840
	11th to 20th	Night	20% 18% 34% 23% 5%	840
	21st to end	Night	19% 15% 40% 26% 1	924
February	1st to 10th	Night	21% 13% 40% 23% 3	840
	11th to 20th	Night	28% 18% 37% 16% 1	823
	21st to end	Night	22% 17% 37% 21% 2	692
March	1st to 10th	Night	19% 15% 38% 25% 4	840
	11th to 20th	Night	21% 16% 36% 22% 4	840
	21st to end	Night	19% 14% 41% 21% 4	924
April	1st to 10th	Night	17% 18% 40% 22% 3	840
	11th to 20th	Night	15% 11% 40% 25% 8%	831
	21st to end	Night	17% 9% 35% 33% 6%	840
May	1st to 10th	Night	17% 12% 36% 27% 7%	796
	11th to 20th	Night	15% 5% 32% 36% 11% 1	554
	21st to end	Night	17% 3 24% 36% 18% 1	455
June	1st to 10th	Night	11% 3 22% 44% 19% 2	420
	11th to 20th	Night	11% 2 23% 44% 18% 2	420
	21st to end	Night	9% 3 22% 45% 21% 1	420
July	1st to 10th	Night	10% 1 18% 43% 26% 2	410
	11th to 20th	Night	6% 2 13% 41% 35% 4	582
	21st to end	Night	9% 2 19% 41% 26% 3	690
August	1st to 10th	Night	10% 2 14% 45% 25% 4	627
	11th to 20th	Night	12% 2 17% 41% 26% 4	776
	21st to end	Night	11% 2 15% 37% 29% 5%	924
September	1st to 10th	Night	14% 3 16% 37% 27% 4	840
	11th to 20th	Night	15% 3 17% 32% 28% 4	840
	21st to end	Night	25% 6% 20% 31% 16% 1	840
October	1st to 10th	Night	18% 4 21% 30% 23% 4	840
	11th to 20th	Night	18% 9% 26% 30% 15% 1	840
	21st to end	Night	16% 9% 28% 30% 16% 1	913
November	1st to 10th	Night	17% 8% 28% 33% 13% 2	820
	11th to 20th	Night	18% 11% 33% 28% 10%	840
	21st to end	Night	14% 13% 32% 30% 11% 1	840
December	1st to 10th	Night	21% 14% 33% 25% 7% 1	840
	11th to 20th	Night	19% 10% 37% 28% 6%	840
	21st to end	Night	19% 12% 33% 30% 6%	924

Page generated at 2026-10-26 04:37:52. Version ac07

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