Spodue Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Spodue Lookout clear sky chart from 2005-11-06 to 2024-11-01.

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	9% 9% 2 5% 3 3 3 3 4 5% 54%	101476
	Night	10% 10% 3 5% 3 3 3 3 4 6% 49%	97637
Transparency	Day	32% 5% 9% 18% 21% 15%	101220
	Night	35% 6% 11% 19% 18% 11%	97482
Seeing	Day	14% 12% 23% 26% 18% 7%	14799
	Night	14% 7% 19% 35% 21% 3	23887

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	15% 19% 7% 9% 4 4 4 3 3 5% 25%	2539
	11th to 20th	Day	24% 20% 6% 6% 3 3 3 2 4 4 25%	2540
	21st to end	Day	21% 16% 4 8% 4 3 3 3 4 5% 28%	3114
February	1st to 10th	Day	12% 16% 3 7% 4 4 3 3 5% 8% 36%	1710
	11th to 20th	Day	12% 18% 4 6% 4 4 4 2 4 6% 36%	1701
	21st to end	Day	11% 18% 6% 8% 5% 4 4 3 4 6% 32%	1570
March	1st to 10th	Day	13% 20% 7% 10% 5% 4 3 2 3 5% 27%	3193
	11th to 20th	Day	9% 14% 3 5% 3 3 2 2 4 5% 51%	3490
	21st to end	Day	13% 19% 4 8% 5% 5% 5% 4 5% 7% 25%	3993
April	1st to 10th	Day	13% 16% 4 8% 5% 3 3 3 4 6% 34%	2280
	11th to 20th	Day	11% 14% 3 7% 4 4 4 4 5% 6% 38%	2249
	21st to end	Day	7% 12% 2 6% 5% 4 3 2 5% 7% 46%	2284
May	1st to 10th	Day	9% 12% 3 5% 3 3 3 3 4 4 51%	4344
	11th to 20th	Day	6% 5% 2 3 2 2 3 2 4 5% 66%	4377
	21st to end	Day	6% 8% 2 5% 4 4 3 3 4 7% 53%	4813
June	1st to 10th	Day	10% 6% 2 5% 5% 5% 5% 4 5% 7% 47%	2660
	11th to 20th	Day	5% 5% 2 4 3 3 3 3 5% 6% 62%	2660
	21st to end	Day	5% 3 1 3 2 3 2 2 3 5% 72%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 3 3 86%	4420
	11th to 20th	Day	2 2 1 3 2 2 2 3 2 4 77%	4420
	21st to end	Day	1 1 1 2 1 1 1 3 4 84%	4775
August	1st to 10th	Day	3 3 1 4 3 3 3 3 5% 5% 69%	4091
	11th to 20th	Day	2 1 1 2 2 2 2 2 3 5% 80%	3941
	21st to end	Day	3 2 1 3 2 2 2 1 3 3 78%	4180
September	1st to 10th	Day	2 2 1 2 2 2 2 2 3 5% 78%	2280
	11th to 20th	Day	4 4 1 4 3 3 3 4 4 5% 64%	2280
	21st to end	Day	5% 5% 1 4 3 3 3 2 4 5% 66%	2037
October	1st to 10th	Day	8% 6% 2 5% 3 2 3 2 5% 6% 60%	1900
	11th to 20th	Day	9% 7% 2 4 3 4 3 4 5% 8% 52%	1900
	21st to end	Day	13% 8% 2 6% 4 3 2 3 4 7% 50%	2038
November	1st to 10th	Day	15% 11% 3 7% 4 3 2 3 5% 6% 41%	1674
	11th to 20th	Day	17% 10% 3 6% 3 3 4 5% 7% 8% 34%	1601
	21st to end	Day	10% 15% 3 7% 3 4 3 4 5% 8% 37%	1520
December	1st to 10th	Day	14% 13% 2 6% 5% 4 3 3 5% 7% 39%	1520
	11th to 20th	Day	22% 15% 3 6% 4 3 3 3 6% 8% 26%	1928
	21st to end	Day	14% 17% 5% 10% 6% 4 5% 3 4 6% 26%	2794
January	1st to 10th	Night	13% 20% 4 8% 5% 5% 5% 3 6% 7% 24%	4406
	11th to 20th	Night	19% 19% 4 8% 3 3 3 2 4 6% 28%	4420
	21st to end	Night	21% 17% 3 7% 4 4 4 3 4 6% 28%	4548
February	1st to 10th	Night	13% 13% 3 7% 4 4 3 4 5% 6% 37%	2470
	11th to 20th	Night	13% 15% 3 7% 4 3 4 3 4 6% 39%	2365
	21st to end	Night	10% 14% 6% 7% 4 4 4 4 5% 8% 35%	1884
March	1st to 10th	Night	11% 21% 5% 10% 4 4 4 3 4 5% 30%	3679
	11th to 20th	Night	11% 12% 2 4 3 2 3 2 3 5% 53%	3490
	21st to end	Night	10% 16% 5% 10% 5% 6% 6% 4 6% 7% 25%	3659
April	1st to 10th	Night	14% 12% 3 7% 4 4 4 3 4 6% 38%	1900
	11th to 20th	Night	9% 11% 3 6% 5% 3 4 4 5% 6% 44%	1879
	21st to end	Night	10% 9% 2 5% 3 3 4 4 6% 8% 47%	1894
May	1st to 10th	Night	9% 11% 3 5% 3 3 3 2 4 5% 53%	2617
	11th to 20th	Night	4 4 1 3 2 2 3 2 4 5% 68%	2516
	21st to end	Night	5% 5% 2 4 3 2 3 2 4 6% 63%	2762
June	1st to 10th	Night	11% 6% 2 5% 3 4 3 3 6% 8% 49%	1520
	11th to 20th	Night	5% 5% 2 3 3 3 2 2 4 6% 65%	1520
	21st to end	Night	4 2 1 3 2 3 2 2 3 4 74%	1520
July	1st to 10th	Night	1 1 1 1 1 1 2 3 3 85%	2540
	11th to 20th	Night	1 2 1 3 3 2 2 2 3 4 77%	2540
	21st to end	Night	1 1 2 2 2 2 2 3 3 81%	2761
August	1st to 10th	Night	2 2 1 3 2 2 3 4 5% 5% 70%	2848
	11th to 20th	Night	2 2 1 2 2 2 3 2 4 4 77%	2898
	21st to end	Night	2 3 1 3 2 2 2 2 3 4 78%	3498
September	1st to 10th	Night	1 1 1 2 1 2 2 2 4 4 80%	1900
	11th to 20th	Night	3 4 1 4 2 3 3 2 6% 6% 67%	1900
	21st to end	Night	6% 4 1 3 2 2 2 2 4 5% 69%	2140
October	1st to 10th	Night	5% 4 1 3 3 2 4 3 4 6% 65%	2280
	11th to 20th	Night	10% 5% 2 5% 4 3 3 3 4 5% 58%	2280
	21st to end	Night	10% 6% 3 5% 3 4 4 3 5% 7% 50%	2560
November	1st to 10th	Night	15% 11% 3 6% 5% 4 4 3 4 7% 39%	2411
	11th to 20th	Night	17% 10% 3 4 4 3 5% 4 6% 9% 35%	2574
	21st to end	Night	11% 13% 2 6% 4 3 4 3 5% 7% 42%	2660
December	1st to 10th	Night	16% 11% 3 6% 3 3 3 2 5% 8% 40%	2660
	11th to 20th	Night	19% 16% 4 7% 4 4 4 4 5% 7% 28%	3276
	21st to end	Night	15% 16% 4 7% 5% 4 4 4 4 6% 30%	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	59% 8% 12% 15% 5%	2539
	11th to 20th	Day	64% 4 8% 13% 6% 4	2540
	21st to end	Day	57% 7% 12% 15% 7% 2	3114
February	1st to 10th	Day	47% 7% 15% 19% 11% 1	1710
	11th to 20th	Day	47% 7% 13% 17% 14% 3	1710
	21st to end	Day	51% 6% 14% 14% 11% 3	1570
March	1st to 10th	Day	58% 7% 9% 15% 10% 1	3193
	11th to 20th	Day	36% 4 13% 24% 22% 1	3490
	21st to end	Day	55% 9% 13% 17% 6% 1	3993
April	1st to 10th	Day	51% 7% 11% 18% 11% 3	2280
	11th to 20th	Day	46% 5% 13% 21% 12% 4	2252
	21st to end	Day	36% 7% 15% 24% 16% 3	2284
May	1st to 10th	Day	35% 6% 8% 25% 24% 3	4344
	11th to 20th	Day	22% 3 7% 18% 38% 11%	4380
	21st to end	Day	30% 6% 13% 30% 20% 1	4814
June	1st to 10th	Day	34% 7% 12% 25% 20% 1	2660
	11th to 20th	Day	22% 5% 9% 28% 27% 8%	2660
	21st to end	Day	17% 3 6% 23% 33% 17%	2660
July	1st to 10th	Day	7% 1 4 11% 18% 59%	4351
	11th to 20th	Day	12% 3 3 11% 19% 52%	4345
	21st to end	Day	8% 1 3 13% 36% 39%	4624
August	1st to 10th	Day	17% 2 4 11% 25% 40%	4076
	11th to 20th	Day	10% 2 3 20% 42% 24%	3980
	21st to end	Day	13% 1 5% 22% 30% 29%	4179
September	1st to 10th	Day	11% 2 4 15% 32% 35%	2280
	11th to 20th	Day	20% 5% 9% 18% 31% 17%	2280
	21st to end	Day	20% 5% 9% 22% 25% 18%	2037
October	1st to 10th	Day	26% 4 10% 18% 27% 15%	1900
	11th to 20th	Day	29% 5% 13% 22% 21% 9%	1900
	21st to end	Day	35% 5% 11% 20% 21% 7%	2038
November	1st to 10th	Day	42% 6% 12% 19% 18% 3	1674
	11th to 20th	Day	46% 8% 18% 14% 12% 3	1601
	21st to end	Day	44% 7% 12% 16% 16% 5%	1520
December	1st to 10th	Day	44% 6% 12% 22% 13% 3	1520
	11th to 20th	Day	55% 7% 14% 14% 10% 1	1928
	21st to end	Day	58% 8% 11% 15% 7% 1	2794
January	1st to 10th	Night	56% 10% 14% 14% 5% 1	4406
	11th to 20th	Night	57% 7% 10% 14% 8% 4	4420
	21st to end	Night	58% 7% 10% 14% 9% 2	4548
February	1st to 10th	Night	45% 7% 15% 18% 12% 3	2470
	11th to 20th	Night	45% 7% 14% 19% 13% 3	2367
	21st to end	Night	46% 9% 15% 17% 10% 3	1884
March	1st to 10th	Night	53% 7% 12% 17% 9% 1	3679
	11th to 20th	Night	34% 5% 11% 27% 22%	3490
	21st to end	Night	52% 13% 13% 14% 7% 1	3659
April	1st to 10th	Night	45% 7% 16% 19% 12% 2	1900
	11th to 20th	Night	40% 6% 16% 22% 13% 4	1879
	21st to end	Night	34% 8% 19% 25% 12% 3	1894
May	1st to 10th	Night	31% 7% 12% 28% 19% 3	2617
	11th to 20th	Night	19% 5% 10% 27% 37% 3	2516
	21st to end	Night	22% 6% 18% 38% 15% 1	2762
June	1st to 10th	Night	32% 7% 15% 28% 17% 1	1520
	11th to 20th	Night	21% 5% 9% 34% 23% 7%	1520
	21st to end	Night	15% 3 8% 30% 33% 12%	1520
July	1st to 10th	Night	6% 2 5% 13% 19% 55%	2500
	11th to 20th	Night	11% 3 4 11% 23% 48%	2492
	21st to end	Night	10% 2 4 12% 34% 39%	2674
August	1st to 10th	Night	15% 3 5% 14% 29% 33%	2839
	11th to 20th	Night	12% 2 4 24% 36% 22%	2925
	21st to end	Night	13% 1 6% 26% 26% 27%	3498
September	1st to 10th	Night	9% 2 4 18% 32% 35%	1900
	11th to 20th	Night	18% 4 9% 21% 30% 18%	1900
	21st to end	Night	19% 3 8% 24% 26% 20%	2140
October	1st to 10th	Night	21% 5% 11% 20% 26% 16%	2280
	11th to 20th	Night	28% 4 12% 25% 22% 10%	2280
	21st to end	Night	31% 7% 13% 20% 18% 10%	2560
November	1st to 10th	Night	44% 6% 11% 18% 16% 4	2411
	11th to 20th	Night	45% 8% 13% 18% 13% 3	2574
	21st to end	Night	41% 7% 13% 16% 16% 7%	2660
December	1st to 10th	Night	43% 7% 13% 19% 15% 3	2660
	11th to 20th	Night	55% 7% 10% 16% 12% 1	3276
	21st to end	Night	53% 9% 12% 14% 11% 2	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	30% 19% 24% 12% 9% 5%	180
	11th to 20th	Day	33% 13% 18% 19% 14% 3	180
	21st to end	Day	20% 13% 23% 22% 18% 5%	388
February	1st to 10th	Day	19% 16% 24% 23% 14% 3	370
	11th to 20th	Day	23% 17% 24% 20% 13% 3	383
	21st to end	Day	19% 18% 26% 27% 8% 1	382
March	1st to 10th	Day	26% 18% 27% 20% 8% 1	460
	11th to 20th	Day	21% 14% 25% 22% 15% 3	460
	21st to end	Day	22% 21% 25% 24% 7% 1	506
April	1st to 10th	Day	21% 18% 24% 25% 9% 3	460
	11th to 20th	Day	21% 21% 25% 19% 11% 4	452
	21st to end	Day	14% 20% 25% 22% 15% 5%	460
May	1st to 10th	Day	13% 17% 26% 25% 14% 4	463
	11th to 20th	Day	19% 15% 23% 21% 15% 7%	488
	21st to end	Day	16% 10% 22% 26% 18% 9%	529
June	1st to 10th	Day	10% 12% 24% 24% 21% 8%	490
	11th to 20th	Day	9% 17% 26% 26% 18% 4	490
	21st to end	Day	4 7% 20% 33% 25% 11%	490
July	1st to 10th	Day	3 5% 24% 37% 23% 8%	486
	11th to 20th	Day	3 3 24% 36% 28% 7%	484
	21st to end	Day	2 3 20% 37% 27% 11%	531
August	1st to 10th	Day	2 2 24% 32% 28% 12%	487
	11th to 20th	Day	3 7% 17% 31% 26% 16%	477
	21st to end	Day	4 6% 19% 32% 27% 12%	539
September	1st to 10th	Day	3 5% 21% 36% 24% 12%	490
	11th to 20th	Day	7% 7% 21% 32% 24% 9%	490
	21st to end	Day	6% 12% 23% 27% 25% 7%	490
October	1st to 10th	Day	11% 10% 24% 25% 21% 9%	490
	11th to 20th	Day	15% 10% 21% 23% 24% 7%	490
	21st to end	Day	17% 12% 26% 21% 17% 8%	487
November	1st to 10th	Day	21% 11% 22% 28% 12% 6%	270
	11th to 20th	Day	19% 8% 21% 28% 16% 8%	219
	21st to end	Day	21% 11% 19% 26% 19% 5%	180
December	1st to 10th	Day	25% 9% 19% 23% 11% 12%	180
	11th to 20th	Day	28% 13% 23% 17% 15% 4	180
	21st to end	Day	22% 15% 22% 24% 16% 2	198
January	1st to 10th	Night	22% 10% 25% 25% 14% 4	760
	11th to 20th	Night	22% 11% 20% 24% 19% 5%	760
	21st to end	Night	19% 9% 18% 31% 17% 5%	836
February	1st to 10th	Night	19% 7% 23% 33% 16% 3	760
	11th to 20th	Night	19% 10% 22% 33% 14% 2	744
	21st to end	Night	17% 11% 22% 36% 14% 1	628
March	1st to 10th	Night	22% 13% 24% 27% 13% 2	760
	11th to 20th	Night	18% 11% 21% 29% 20% 2	760
	21st to end	Night	20% 13% 26% 29% 11% 1	836
April	1st to 10th	Night	18% 10% 24% 32% 14% 2	760
	11th to 20th	Night	13% 11% 30% 27% 15% 4	751
	21st to end	Night	13% 11% 23% 32% 19% 2	754
May	1st to 10th	Night	11% 4 30% 35% 19% 1	431
	11th to 20th	Night	9% 7% 18% 40% 24% 2	374
	21st to end	Night	10% 6% 23% 36% 22% 2	411
June	1st to 10th	Night	11% 5% 18% 41% 24% 1	380
	11th to 20th	Night	6% 5% 27% 44% 16% 1	380
	21st to end	Night	4 1 16% 52% 26% 1	380
July	1st to 10th	Night	2 1 14% 53% 29% 1	370
	11th to 20th	Night	1 1 16% 57% 25%	368
	21st to end	Night	2 1 10% 55% 31% 1	416
August	1st to 10th	Night	2 1 7% 48% 39% 3	567
	11th to 20th	Night	2 1 10% 43% 39% 5%	611
	21st to end	Night	4 2 13% 44% 34% 2	836
September	1st to 10th	Night	1 1 16% 43% 35% 4	760
	11th to 20th	Night	5% 4 14% 35% 35% 7%	760
	21st to end	Night	8% 4 16% 36% 29% 7%	760
October	1st to 10th	Night	5% 4 20% 38% 28% 4	760
	11th to 20th	Night	11% 8% 13% 35% 28% 5%	760
	21st to end	Night	13% 7% 18% 34% 21% 7%	836
November	1st to 10th	Night	20% 7% 19% 34% 15% 4	742
	11th to 20th	Night	22% 8% 19% 33% 14% 3	760
	21st to end	Night	16% 9% 19% 32% 20% 4	760
December	1st to 10th	Night	22% 8% 16% 33% 17% 5%	760
	11th to 20th	Night	25% 7% 18% 32% 15% 3	760
	21st to end	Night	25% 15% 21% 28% 9% 2	836

Page generated at 2024-10-29 08:20:51. Version ac07

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