Dedication Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dedication Point clear sky chart from 2005-11-06 to 2024-11-08.

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	6% 6% 2 5% 4 4 4 3 5% 7% 55%	105161
	Night	8% 7% 2 6% 4 4 4 4 5% 7% 50%	102627
Transparency	Day	27% 6% 11% 20% 21% 15%	104905
	Night	32% 6% 12% 20% 18% 12%	102472
Seeing	Day	7% 9% 25% 30% 21% 8%	14512
	Night	8% 6% 23% 37% 22% 3	23827

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	10% 14% 3 9% 7% 6% 6% 4 6% 9% 25%	2539
	11th to 20th	Day	12% 16% 5% 12% 7% 6% 5% 4 6% 6% 21%	2540
	21st to end	Day	14% 13% 5% 13% 7% 5% 5% 4 5% 7% 24%	2794
February	1st to 10th	Day	8% 8% 5% 10% 6% 4 6% 5% 5% 7% 35%	1698
	11th to 20th	Day	8% 12% 3 8% 6% 4 5% 4 6% 8% 37%	1850
	21st to end	Day	6% 10% 3 8% 6% 6% 5% 5% 7% 7% 37%	1570
March	1st to 10th	Day	7% 11% 5% 9% 6% 7% 6% 5% 8% 8% 30%	3138
	11th to 20th	Day	5% 5% 2 5% 3 3 4 4 5% 6% 57%	3351
	21st to end	Day	7% 8% 3 8% 6% 6% 7% 6% 8% 11% 32%	4023
April	1st to 10th	Day	9% 7% 2 5% 6% 5% 4 4 6% 9% 41%	2280
	11th to 20th	Day	5% 6% 3 8% 5% 4 4 4 6% 7% 47%	2277
	21st to end	Day	7% 5% 2 5% 4 3 5% 4 6% 8% 51%	2470
May	1st to 10th	Day	7% 6% 2 5% 4 4 5% 4 5% 7% 52%	4110
	11th to 20th	Day	5% 3 1 3 2 2 3 2 4 6% 68%	4190
	21st to end	Day	5% 4 2 4 4 4 4 4 6% 8% 57%	4813
June	1st to 10th	Day	7% 6% 2 5% 4 4 5% 5% 7% 9% 47%	2660
	11th to 20th	Day	6% 4 1 4 3 3 3 3 5% 8% 61%	2660
	21st to end	Day	2 2 1 2 2 2 3 3 5% 5% 73%	2660
July	1st to 10th	Day	1 1 1 2 1 3 2 4 3 82%	4420
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 4 78%	4420
	21st to end	Day	3 2 1 2 2 2 3 2 4 5% 75%	4790
August	1st to 10th	Day	3 4 1 4 2 3 4 3 5% 6% 65%	4224
	11th to 20th	Day	1 1 1 2 2 2 2 2 3 4 80%	4007
	21st to end	Day	2 3 1 3 2 2 2 2 3 3 78%	4180
September	1st to 10th	Day	1 2 1 3 2 2 2 2 3 5% 77%	2280
	11th to 20th	Day	4 3 2 4 3 2 2 2 5% 7% 66%	2110
	21st to end	Day	5% 3 1 4 2 3 3 3 4 5% 68%	2090
October	1st to 10th	Day	4 3 1 3 3 3 3 3 3 4 70%	3490
	11th to 20th	Day	5% 6% 2 4 3 3 3 3 6% 7% 58%	3050
	21st to end	Day	5% 5% 2 6% 4 4 4 4 6% 8% 51%	3101
November	1st to 10th	Day	9% 8% 2 6% 5% 5% 4 4 5% 9% 42%	1737
	11th to 20th	Day	11% 7% 2 7% 5% 5% 5% 5% 7% 9% 38%	1710
	21st to end	Day	8% 7% 2 8% 6% 5% 6% 5% 6% 9% 37%	1687
December	1st to 10th	Day	12% 9% 3 12% 5% 4 4 4 6% 7% 34%	1520
	11th to 20th	Day	13% 10% 4 12% 7% 5% 5% 4 6% 7% 25%	1928
	21st to end	Day	8% 10% 4 12% 8% 6% 6% 4 7% 7% 28%	2794
January	1st to 10th	Night	10% 13% 5% 11% 8% 6% 7% 5% 6% 8% 21%	4406
	11th to 20th	Night	15% 16% 4 11% 6% 6% 5% 4 6% 6% 20%	4420
	21st to end	Night	15% 11% 5% 12% 6% 5% 5% 4 5% 5% 28%	4862
February	1st to 10th	Night	11% 9% 3 7% 4 6% 5% 4 6% 6% 38%	2476
	11th to 20th	Night	9% 7% 3 7% 5% 5% 4 5% 6% 10% 40%	2218
	21st to end	Night	8% 11% 3 7% 6% 5% 5% 5% 8% 7% 36%	1884
March	1st to 10th	Night	8% 10% 3 8% 4 4 6% 5% 8% 9% 36%	3736
	11th to 20th	Night	7% 9% 2 5% 3 4 3 2 4 6% 55%	3628
	21st to end	Night	9% 9% 2 7% 5% 5% 6% 5% 7% 9% 35%	3626
April	1st to 10th	Night	9% 7% 2 6% 5% 4 5% 4 6% 6% 46%	1900
	11th to 20th	Night	7% 5% 2 6% 4 5% 6% 3 5% 7% 49%	1850
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 7% 53%	1710
May	1st to 10th	Night	8% 5% 2 6% 3 5% 4 3 6% 8% 51%	2860
	11th to 20th	Night	4 3 1 3 3 3 4 3 4 6% 67%	2707
	21st to end	Night	6% 4 2 5% 4 4 4 3 5% 7% 57%	2762
June	1st to 10th	Night	8% 5% 2 5% 4 5% 4 4 6% 8% 48%	1520
	11th to 20th	Night	6% 4 2 3 3 3 3 3 6% 6% 62%	1520
	21st to end	Night	3 2 3 3 2 3 3 5% 6% 69%	1520
July	1st to 10th	Night	1 1 1 2 2 2 2 3 4 83%	2540
	11th to 20th	Night	1 1 2 2 2 3 2 4 4 80%	2540
	21st to end	Night	1 2 1 4 3 3 3 3 4 6% 69%	2761
August	1st to 10th	Night	4 4 1 3 3 3 3 4 5% 6% 64%	2710
	11th to 20th	Night	1 1 2 2 2 3 2 4 5% 79%	2830
	21st to end	Night	4 2 1 2 1 2 2 2 3 4 77%	3498
September	1st to 10th	Night	3 3 1 3 2 1 2 2 4 4 76%	1900
	11th to 20th	Night	4 3 2 3 3 3 4 2 5% 6% 66%	2069
	21st to end	Night	5% 3 1 3 2 3 3 2 4 5% 68%	2090
October	1st to 10th	Night	4 2 1 3 2 2 3 2 4 5% 72%	3490
	11th to 20th	Night	5% 4 1 4 3 3 3 3 4 6% 64%	3878
	21st to end	Night	8% 6% 2 5% 4 4 5% 4 6% 8% 50%	4457
November	1st to 10th	Night	10% 8% 2 6% 4 4 4 4 5% 7% 45%	2502
	11th to 20th	Night	14% 6% 2 6% 4 5% 5% 4 6% 8% 39%	2470
	21st to end	Night	9% 8% 3 7% 4 4 4 5% 6% 8% 43%	2489
December	1st to 10th	Night	11% 10% 4 9% 6% 5% 5% 3 6% 7% 35%	2660
	11th to 20th	Night	13% 10% 4 10% 6% 6% 6% 5% 6% 7% 27%	3276
	21st to end	Night	11% 11% 4 10% 6% 5% 5% 4 6% 8% 29%	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	50% 12% 19% 16% 3	2539
	11th to 20th	Day	58% 13% 16% 13% 1	2540
	21st to end	Day	56% 10% 19% 12% 2	2794
February	1st to 10th	Day	45% 9% 19% 21% 5% 1	1698
	11th to 20th	Day	42% 9% 18% 23% 9%	1860
	21st to end	Day	41% 8% 18% 22% 11% 1	1570
March	1st to 10th	Day	43% 10% 15% 22% 9% 1	3138
	11th to 20th	Day	25% 6% 11% 40% 16% 1	3351
	21st to end	Day	38% 11% 19% 22% 8% 3	4023
April	1st to 10th	Day	38% 6% 15% 22% 15% 4	2280
	11th to 20th	Day	33% 6% 14% 24% 18% 5%	2280
	21st to end	Day	29% 7% 12% 28% 20% 4	2470
May	1st to 10th	Day	28% 5% 11% 24% 27% 6%	4110
	11th to 20th	Day	18% 4 7% 22% 35% 14%	4193
	21st to end	Day	22% 6% 14% 29% 25% 4	4814
June	1st to 10th	Day	31% 7% 13% 25% 21% 3	2660
	11th to 20th	Day	21% 5% 9% 23% 31% 12%	2660
	21st to end	Day	13% 3 7% 18% 35% 25%	2660
July	1st to 10th	Day	8% 2 4 9% 17% 60%	4351
	11th to 20th	Day	10% 2 3 6% 21% 58%	4345
	21st to end	Day	13% 2 4 6% 31% 44%	4639
August	1st to 10th	Day	19% 3 5% 10% 25% 37%	4208
	11th to 20th	Day	9% 2 4 14% 35% 36%	4046
	21st to end	Day	13% 2 4 14% 37% 31%	4179
September	1st to 10th	Day	12% 2 5% 14% 32% 35%	2280
	11th to 20th	Day	20% 4 8% 24% 27% 17%	2110
	21st to end	Day	20% 3 7% 23% 35% 12%	2090
October	1st to 10th	Day	19% 3 7% 17% 41% 13%	3490
	11th to 20th	Day	26% 3 12% 29% 26% 4	3050
	21st to end	Day	28% 4 13% 32% 21% 2	3101
November	1st to 10th	Day	38% 6% 14% 27% 13%	1737
	11th to 20th	Day	38% 9% 21% 26% 6% 1	1710
	21st to end	Day	40% 9% 21% 25% 5%	1687
December	1st to 10th	Day	45% 11% 20% 16% 7%	1520
	11th to 20th	Day	52% 8% 23% 14% 3	1928
	21st to end	Day	46% 11% 19% 19% 5%	2794
January	1st to 10th	Night	52% 11% 21% 13% 3	4406
	11th to 20th	Night	57% 13% 13% 13% 3	4420
	21st to end	Night	53% 10% 18% 16% 3	4862
February	1st to 10th	Night	43% 10% 21% 23% 4	2476
	11th to 20th	Night	37% 8% 18% 24% 11% 1	2219
	21st to end	Night	41% 8% 16% 22% 12% 1	1884
March	1st to 10th	Night	38% 9% 15% 25% 12% 1	3736
	11th to 20th	Night	30% 5% 9% 32% 22% 2	3628
	21st to end	Night	37% 11% 15% 29% 8% 1	3626
April	1st to 10th	Night	36% 6% 12% 26% 17% 3	1900
	11th to 20th	Night	32% 5% 10% 28% 21% 4	1850
	21st to end	Night	28% 5% 11% 29% 24% 3	1710
May	1st to 10th	Night	26% 5% 11% 24% 27% 7%	2860
	11th to 20th	Night	17% 4 9% 18% 42% 11%	2707
	21st to end	Night	25% 6% 12% 24% 29% 4	2762
June	1st to 10th	Night	32% 7% 13% 22% 23% 3	1520
	11th to 20th	Night	22% 5% 8% 21% 34% 11%	1520
	21st to end	Night	15% 3 6% 18% 31% 28%	1520
July	1st to 10th	Night	8% 1 3 8% 19% 61%	2500
	11th to 20th	Night	9% 2 3 5% 18% 63%	2492
	21st to end	Night	16% 2 4 6% 29% 43%	2674
August	1st to 10th	Night	20% 3 5% 9% 23% 40%	2702
	11th to 20th	Night	10% 2 3 10% 27% 47%	2857
	21st to end	Night	13% 2 3 11% 33% 37%	3498
September	1st to 10th	Night	13% 2 4 11% 29% 40%	1900
	11th to 20th	Night	19% 4 6% 19% 25% 27%	2069
	21st to end	Night	19% 3 5% 20% 33% 20%	2090
October	1st to 10th	Night	17% 3 6% 16% 33% 26%	3490
	11th to 20th	Night	22% 3 6% 29% 34% 6%	3878
	21st to end	Night	31% 5% 10% 28% 23% 3	4457
November	1st to 10th	Night	36% 6% 12% 26% 18% 2	2502
	11th to 20th	Night	39% 7% 14% 28% 11%	2470
	21st to end	Night	37% 6% 17% 29% 10%	2489
December	1st to 10th	Night	45% 8% 21% 17% 7% 1	2660
	11th to 20th	Night	50% 10% 19% 19% 3	3276
	21st to end	Night	46% 12% 19% 18% 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	14% 12% 28% 24% 17% 4	180
	11th to 20th	Day	11% 8% 31% 27% 19% 5%	180
	21st to end	Day	12% 6% 27% 35% 17% 4	198
February	1st to 10th	Day	8% 17% 32% 22% 17% 4	305
	11th to 20th	Day	13% 13% 31% 25% 13% 5%	455
	21st to end	Day	9% 16% 29% 28% 15% 3	382
March	1st to 10th	Day	10% 13% 35% 29% 10% 2	460
	11th to 20th	Day	9% 11% 30% 29% 17% 4	460
	21st to end	Day	10% 14% 32% 26% 14% 3	506
April	1st to 10th	Day	12% 18% 26% 20% 18% 6%	460
	11th to 20th	Day	5% 16% 34% 26% 14% 5%	452
	21st to end	Day	8% 14% 33% 26% 15% 4	460
May	1st to 10th	Day	3 15% 31% 31% 15% 4	463
	11th to 20th	Day	13% 9% 23% 27% 20% 8%	488
	21st to end	Day	7% 6% 19% 33% 21% 14%	529
June	1st to 10th	Day	7% 6% 26% 29% 22% 10%	490
	11th to 20th	Day	5% 11% 27% 32% 19% 6%	490
	21st to end	Day	3 5% 28% 31% 22% 11%	490
July	1st to 10th	Day	2 3 23% 41% 21% 10%	486
	11th to 20th	Day	1 2 25% 43% 23% 6%	484
	21st to end	Day	2 2 21% 35% 32% 8%	531
August	1st to 10th	Day	3 2 24% 35% 28% 9%	487
	11th to 20th	Day	2 1 20% 36% 28% 13%	477
	21st to end	Day	4 4 19% 32% 26% 16%	539
September	1st to 10th	Day	3 3 16% 29% 32% 16%	490
	11th to 20th	Day	4 5% 18% 30% 30% 13%	490
	21st to end	Day	4 5% 22% 32% 26% 11%	490
October	1st to 10th	Day	7% 7% 19% 26% 27% 15%	490
	11th to 20th	Day	8% 7% 20% 27% 26% 12%	392
	21st to end	Day	9% 10% 22% 31% 21% 7%	330
November	1st to 10th	Day	10% 11% 24% 33% 18% 3	291
	11th to 20th	Day	7% 8% 27% 32% 19% 6%	270
	21st to end	Day	8% 6% 25% 33% 24% 3	259
December	1st to 10th	Day	14% 8% 24% 26% 18% 9%	180
	11th to 20th	Day	13% 11% 29% 28% 16% 3	180
	21st to end	Day	10% 14% 29% 27% 16% 4	198
January	1st to 10th	Night	11% 6% 28% 33% 18% 4	760
	11th to 20th	Night	10% 6% 27% 33% 20% 3	760
	21st to end	Night	12% 4 22% 34% 24% 4	836
February	1st to 10th	Night	12% 8% 28% 35% 16% 1	760
	11th to 20th	Night	10% 5% 27% 38% 17% 2	744
	21st to end	Night	9% 7% 31% 37% 14% 1	628
March	1st to 10th	Night	11% 8% 32% 34% 14% 2	760
	11th to 20th	Night	10% 7% 27% 36% 17% 3	760
	21st to end	Night	12% 10% 29% 34% 14% 1	836
April	1st to 10th	Night	9% 9% 25% 35% 19% 2	760
	11th to 20th	Night	8% 10% 26% 37% 17% 2	722
	21st to end	Night	7% 9% 28% 39% 15% 3	570
May	1st to 10th	Night	6% 9% 33% 33% 18% 2	570
	11th to 20th	Night	5% 7% 25% 36% 23% 5%	487
	21st to end	Night	6% 6% 23% 34% 25% 6%	411
June	1st to 10th	Night	8% 6% 21% 38% 20% 6%	380
	11th to 20th	Night	6% 8% 29% 33% 21% 2	380
	21st to end	Night	2 5% 25% 39% 26% 3	380
July	1st to 10th	Night	1 3 20% 48% 26% 2	370
	11th to 20th	Night	1 2 21% 52% 24%	368
	21st to end	Night	1 1 16% 49% 29% 2	416
August	1st to 10th	Night	5% 3 14% 44% 33% 1	481
	11th to 20th	Night	1 1 13% 51% 32% 2	570
	21st to end	Night	3 3 16% 43% 29% 6%	836
September	1st to 10th	Night	3 1 13% 41% 37% 5%	760
	11th to 20th	Night	5% 3 13% 39% 35% 6%	760
	21st to end	Night	6% 4 17% 33% 30% 9%	760
October	1st to 10th	Night	7% 4 18% 37% 29% 5%	760
	11th to 20th	Night	6% 5% 17% 39% 27% 6%	760
	21st to end	Night	7% 6% 22% 38% 23% 4	836
November	1st to 10th	Night	10% 5% 21% 38% 24% 2	770
	11th to 20th	Night	14% 7% 24% 34% 19% 3	760
	21st to end	Night	11% 4 23% 37% 23% 3	760
December	1st to 10th	Night	11% 6% 25% 38% 17% 3	760
	11th to 20th	Night	14% 6% 22% 38% 18% 2	760
	21st to end	Night	18% 6% 29% 34% 12% 1	836

Page generated at 2024-11-05 06:15:51. Version ac07

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