AUGO
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the AUGO clear sky chart from 2005-11-06 to 2024-11-03.

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	10% 9% 3 9% 6% 5% 5% 4 6% 8% 34%	102418
	Night	8% 10% 4 9% 6% 6% 6% 4 6% 8% 33%	96619
Transparency	Day	47% 7% 18% 22% 7%	102154
	Night	47% 7% 16% 21% 8% 1	96529
Seeing	Day	14% 7% 25% 30% 19% 6%	16143
	Night	13% 5% 26% 37% 17% 2	24518

By Month

Percentage Cloud Cover NW (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	4 17% 7% 15% 11% 6% 5% 6% 6% 6% 19%	2057
	11th to 20th	Day	5% 9% 3 10% 7% 6% 6% 8% 8% 11% 28%	2199
	21st to end	Day	6% 12% 4 11% 6% 5% 5% 4 6% 8% 33%	2520
February	1st to 10th	Day	7% 14% 5% 10% 8% 7% 7% 5% 8% 7% 24%	1520
	11th to 20th	Day	6% 11% 5% 13% 8% 6% 5% 4 7% 8% 27%	1590
	21st to end	Day	5% 11% 5% 12% 8% 7% 7% 6% 7% 7% 24%	1437
March	1st to 10th	Day	3 11% 5% 12% 9% 6% 7% 4 6% 9% 28%	3138
	11th to 20th	Day	5% 9% 5% 10% 6% 5% 5% 4 6% 9% 37%	3454
	21st to end	Day	10% 16% 5% 17% 6% 5% 5% 3 5% 7% 22%	3881
April	1st to 10th	Day	8% 12% 4 9% 7% 7% 6% 6% 6% 7% 29%	2394
	11th to 20th	Day	11% 11% 3 8% 6% 7% 5% 5% 6% 7% 31%	2440
	21st to end	Day	13% 11% 4 10% 6% 6% 6% 4 8% 8% 26%	2480
May	1st to 10th	Day	18% 9% 3 7% 5% 5% 4 3 6% 7% 31%	4740
	11th to 20th	Day	15% 11% 3 8% 6% 4 5% 4 6% 6% 32%	4694
	21st to end	Day	11% 9% 3 9% 7% 7% 6% 5% 8% 9% 26%	5161
June	1st to 10th	Day	16% 7% 3 8% 6% 6% 5% 5% 6% 7% 30%	2907
	11th to 20th	Day	19% 10% 3 7% 6% 5% 7% 5% 7% 8% 23%	3040
	21st to end	Day	10% 5% 2 8% 6% 5% 7% 5% 7% 9% 35%	3040
July	1st to 10th	Day	8% 5% 3 6% 4 5% 6% 5% 7% 9% 43%	5060
	11th to 20th	Day	9% 4 1 5% 4 5% 5% 5% 7% 9% 46%	4782
	21st to end	Day	14% 5% 2 6% 3 4 5% 4 7% 9% 42%	5138
August	1st to 10th	Day	12% 7% 2 6% 4 4 4 4 6% 7% 43%	4625
	11th to 20th	Day	10% 6% 2 6% 5% 4 5% 4 6% 10% 42%	4190
	21st to end	Day	11% 5% 2 7% 5% 5% 5% 5% 6% 9% 41%	4521
September	1st to 10th	Day	12% 7% 3 7% 5% 4 4 4 5% 8% 40%	2442
	11th to 20th	Day	14% 7% 2 7% 3 5% 5% 4 6% 9% 37%	2090
	21st to end	Day	8% 7% 2 7% 5% 4 5% 4 7% 8% 43%	2090
October	1st to 10th	Day	11% 10% 3 9% 5% 5% 5% 3 6% 7% 36%	1962
	11th to 20th	Day	12% 11% 3 6% 5% 4 5% 5% 6% 7% 36%	1729
	21st to end	Day	11% 13% 5% 10% 6% 5% 6% 4 5% 5% 29%	1817
November	1st to 10th	Day	11% 16% 4 9% 7% 4 5% 5% 6% 7% 26%	1500
	11th to 20th	Day	5% 13% 5% 13% 7% 6% 5% 4 6% 8% 28%	1330
	21st to end	Day	4 13% 5% 12% 10% 5% 6% 3 7% 6% 31%	1330
December	1st to 10th	Day	4 12% 4 12% 8% 7% 6% 5% 6% 9% 27%	1330
	11th to 20th	Day	9% 11% 4 9% 6% 7% 7% 5% 7% 7% 27%	1682
	21st to end	Day	4 7% 3 10% 6% 5% 6% 4 7% 8% 40%	2108
January	1st to 10th	Night	5% 13% 6% 17% 8% 6% 6% 4 6% 6% 23%	4884
	11th to 20th	Night	4 10% 4 8% 7% 7% 8% 7% 7% 7% 33%	4699
	21st to end	Night	6% 12% 4 11% 8% 6% 6% 4 5% 7% 30%	5153
February	1st to 10th	Night	7% 11% 5% 11% 8% 6% 7% 5% 6% 7% 26%	2660
	11th to 20th	Night	7% 10% 4 12% 8% 6% 6% 5% 7% 7% 29%	2476
	21st to end	Night	3 10% 4 10% 7% 6% 6% 6% 7% 8% 31%	2016
March	1st to 10th	Night	4 10% 5% 11% 7% 7% 6% 5% 6% 10% 29%	3736
	11th to 20th	Night	5% 8% 3 8% 6% 6% 5% 4 7% 10% 38%	3524
	21st to end	Night	8% 15% 7% 14% 6% 5% 5% 4 5% 6% 25%	3771
April	1st to 10th	Night	8% 10% 3 8% 7% 6% 5% 4 7% 8% 34%	1786
	11th to 20th	Night	9% 11% 4 9% 6% 6% 7% 5% 6% 7% 30%	1691
	21st to end	Night	11% 12% 3 8% 5% 5% 5% 4 6% 7% 33%	1697
May	1st to 10th	Night	19% 8% 2 6% 5% 4 5% 4 5% 7% 33%	2220
	11th to 20th	Night	15% 10% 3 8% 5% 6% 5% 5% 5% 7% 32%	2199
	21st to end	Night	13% 7% 2 8% 7% 6% 6% 6% 8% 9% 29%	2414
June	1st to 10th	Night	16% 6% 3 8% 6% 5% 6% 5% 6% 8% 31%	1268
	11th to 20th	Night	18% 9% 2 7% 5% 6% 5% 5% 7% 8% 28%	1140
	21st to end	Night	10% 6% 3 8% 5% 4 6% 4 8% 9% 38%	1140
July	1st to 10th	Night	8% 5% 2 6% 4 5% 5% 4 7% 9% 45%	1900
	11th to 20th	Night	7% 4 2 6% 4 5% 5% 5% 6% 10% 46%	2175
	21st to end	Night	14% 5% 2 3 4 4 4 3 7% 9% 45%	2414
August	1st to 10th	Night	9% 5% 2 7% 5% 5% 5% 4 5% 8% 44%	2303
	11th to 20th	Night	14% 7% 2 6% 4 4 4 4 5% 9% 41%	2643
	21st to end	Night	12% 5% 2 6% 4 5% 6% 4 7% 8% 41%	3146
September	1st to 10th	Night	12% 6% 3 5% 4 5% 5% 4 6% 8% 43%	1735
	11th to 20th	Night	12% 7% 3 6% 4 3 4 4 5% 8% 43%	2090
	21st to end	Night	10% 6% 2 6% 4 5% 5% 4 6% 8% 45%	2090
October	1st to 10th	Night	11% 9% 3 7% 5% 5% 5% 4 7% 8% 37%	2217
	11th to 20th	Night	9% 9% 4 8% 5% 4 5% 4 6% 7% 37%	2449
	21st to end	Night	11% 12% 4 9% 6% 5% 5% 4 6% 6% 32%	2761
November	1st to 10th	Night	12% 14% 5% 11% 7% 6% 5% 4 5% 6% 27%	2619
	11th to 20th	Night	8% 13% 5% 12% 7% 6% 6% 5% 5% 7% 25%	2850
	21st to end	Night	6% 12% 5% 12% 9% 6% 5% 4 6% 8% 26%	2850
December	1st to 10th	Night	7% 13% 4 10% 8% 6% 5% 5% 6% 8% 30%	2850
	11th to 20th	Night	8% 13% 5% 13% 8% 6% 5% 5% 6% 8% 22%	3510
	21st to end	Night	4 7% 3 8% 6% 6% 6% 4 7% 9% 40%	5543

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	63% 7% 13% 13% 4	2057
	11th to 20th	Day	48% 6% 14% 18% 13% 1	2220
	21st to end	Day	49% 6% 22% 16% 7%	2520
February	1st to 10th	Day	56% 7% 13% 16% 8%	1520
	11th to 20th	Day	54% 7% 16% 16% 7%	1598
	21st to end	Day	54% 8% 17% 15% 7%	1437
March	1st to 10th	Day	52% 6% 16% 20% 6%	3138
	11th to 20th	Day	43% 7% 22% 21% 7%	3455
	21st to end	Day	60% 7% 12% 18% 3	3881
April	1st to 10th	Day	50% 9% 17% 17% 8% 1	2394
	11th to 20th	Day	50% 6% 14% 21% 8%	2440
	21st to end	Day	53% 8% 13% 18% 7% 1	2480
May	1st to 10th	Day	50% 7% 10% 23% 10%	4740
	11th to 20th	Day	49% 7% 10% 24% 10%	4698
	21st to end	Day	49% 10% 17% 16% 7%	5162
June	1st to 10th	Day	50% 7% 15% 21% 6%	2907
	11th to 20th	Day	56% 8% 15% 16% 5%	3040
	21st to end	Day	43% 9% 20% 20% 7%	3040
July	1st to 10th	Day	36% 6% 22% 26% 9% 1	4981
	11th to 20th	Day	34% 7% 17% 31% 12%	4699
	21st to end	Day	39% 6% 22% 28% 5%	4976
August	1st to 10th	Day	41% 6% 20% 30% 2	4607
	11th to 20th	Day	38% 6% 24% 25% 8%	4232
	21st to end	Day	39% 5% 30% 22% 3	4520
September	1st to 10th	Day	41% 8% 19% 24% 7% 1	2442
	11th to 20th	Day	42% 8% 22% 22% 5%	2090
	21st to end	Day	38% 8% 20% 24% 9% 1	2090
October	1st to 10th	Day	47% 7% 21% 19% 6%	1962
	11th to 20th	Day	46% 7% 18% 24% 6%	1729
	21st to end	Day	56% 7% 13% 20% 4	1817
November	1st to 10th	Day	56% 8% 15% 16% 4	1500
	11th to 20th	Day	53% 7% 20% 14% 5%	1330
	21st to end	Day	53% 9% 16% 18% 4 1	1330
December	1st to 10th	Day	52% 9% 14% 17% 8% 1	1330
	11th to 20th	Day	52% 9% 18% 16% 5%	1684
	21st to end	Day	40% 6% 12% 29% 11% 1	2108
January	1st to 10th	Night	59% 7% 13% 14% 6% 1	4884
	11th to 20th	Night	47% 7% 14% 19% 12% 1	4740
	21st to end	Night	52% 7% 21% 14% 5%	5153
February	1st to 10th	Night	54% 7% 14% 17% 7% 1	2660
	11th to 20th	Night	54% 6% 13% 18% 9%	2478
	21st to end	Night	46% 9% 16% 21% 9%	2016
March	1st to 10th	Night	48% 7% 18% 22% 5%	3736
	11th to 20th	Night	39% 7% 22% 22% 9% 1	3524
	21st to end	Night	55% 8% 12% 18% 6%	3771
April	1st to 10th	Night	45% 6% 14% 22% 12% 1	1786
	11th to 20th	Night	50% 7% 10% 18% 12% 2	1691
	21st to end	Night	49% 6% 11% 21% 12% 1	1697
May	1st to 10th	Night	48% 6% 10% 21% 13% 1	2220
	11th to 20th	Night	48% 8% 10% 23% 10% 1	2199
	21st to end	Night	46% 10% 20% 16% 8% 1	2414
June	1st to 10th	Night	50% 6% 15% 19% 9% 1	1268
	11th to 20th	Night	52% 8% 14% 21% 6%	1140
	21st to end	Night	39% 9% 21% 24% 6% 1	1140
July	1st to 10th	Night	34% 7% 21% 25% 11% 1	1870
	11th to 20th	Night	33% 7% 16% 35% 10%	2135
	21st to end	Night	36% 5% 23% 29% 7%	2337
August	1st to 10th	Night	39% 6% 19% 34% 1	2296
	11th to 20th	Night	41% 5% 20% 23% 9%	2667
	21st to end	Night	40% 4 27% 24% 4	3146
September	1st to 10th	Night	38% 7% 21% 26% 6% 2	1735
	11th to 20th	Night	38% 6% 20% 28% 9%	2090
	21st to end	Night	36% 8% 17% 26% 11% 2	2090
October	1st to 10th	Night	44% 6% 16% 25% 9%	2217
	11th to 20th	Night	44% 6% 17% 26% 6%	2449
	21st to end	Night	51% 7% 15% 21% 7%	2761
November	1st to 10th	Night	58% 6% 12% 20% 5%	2619
	11th to 20th	Night	57% 8% 16% 15% 4	2850
	21st to end	Night	55% 8% 18% 15% 4 1	2850
December	1st to 10th	Night	51% 7% 12% 20% 9% 1	2850
	11th to 20th	Night	59% 9% 14% 13% 5%	3507
	21st to end	Night	39% 6% 16% 24% 14% 2	5543

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	9% 4 28% 36% 19% 3	180
	11th to 20th	Day	12% 7% 32% 28% 16% 5%	180
	21st to end	Day	12% 9% 36% 26% 14% 4	198
February	1st to 10th	Day	13% 8% 38% 29% 11% 2	180
	11th to 20th	Day	12% 7% 30% 32% 15% 4	234
	21st to end	Day	8% 7% 35% 32% 14% 6%	249
March	1st to 10th	Day	8% 9% 32% 32% 16% 3	460
	11th to 20th	Day	8% 9% 35% 28% 16% 5%	460
	21st to end	Day	17% 6% 30% 28% 15% 4	506
April	1st to 10th	Day	9% 12% 35% 28% 11% 4	460
	11th to 20th	Day	16% 8% 27% 28% 16% 6%	452
	21st to end	Day	17% 9% 31% 28% 12% 2	465
May	1st to 10th	Day	13% 10% 23% 30% 19% 5%	653
	11th to 20th	Day	14% 7% 24% 30% 19% 5%	675
	21st to end	Day	15% 7% 18% 31% 20% 8%	734
June	1st to 10th	Day	20% 7% 25% 30% 14% 4	737
	11th to 20th	Day	20% 6% 18% 26% 23% 6%	870
	21st to end	Day	12% 3 18% 32% 26% 10%	870
July	1st to 10th	Day	12% 3 17% 33% 25% 9%	856
	11th to 20th	Day	14% 4 19% 30% 25% 8%	695
	21st to end	Day	11% 5% 19% 29% 26% 10%	739
August	1st to 10th	Day	14% 4 16% 28% 24% 15%	620
	11th to 20th	Day	10% 4 27% 30% 23% 6%	477
	21st to end	Day	11% 6% 22% 31% 23% 6%	539
September	1st to 10th	Day	17% 11% 25% 24% 17% 6%	490
	11th to 20th	Day	20% 7% 24% 30% 15% 4	490
	21st to end	Day	12% 11% 30% 28% 16% 4	490
October	1st to 10th	Day	14% 10% 30% 27% 15% 4	362
	11th to 20th	Day	16% 4 33% 31% 14% 2	300
	21st to end	Day	18% 12% 31% 25% 12% 4	330
November	1st to 10th	Day	20% 5% 28% 31% 15% 2	274
	11th to 20th	Day	12% 7% 40% 25% 13% 3	180
	21st to end	Day	7% 7% 42% 28% 12% 4	180
December	1st to 10th	Day	6% 8% 33% 31% 17% 6%	180
	11th to 20th	Day	12% 9% 32% 34% 11% 2	180
	21st to end	Day	8% 4 24% 37% 22% 6%	198
January	1st to 10th	Night	12% 6% 29% 38% 13% 1	993
	11th to 20th	Night	11% 6% 32% 37% 13% 2	950
	21st to end	Night	14% 7% 34% 32% 10% 2	1010
February	1st to 10th	Night	12% 7% 27% 34% 18% 2	760
	11th to 20th	Night	12% 4 28% 38% 18% 1	744
	21st to end	Night	6% 4 29% 38% 20% 4	628
March	1st to 10th	Night	10% 5% 28% 39% 16% 2	760
	11th to 20th	Night	12% 5% 28% 39% 15% 1	760
	21st to end	Night	14% 5% 27% 36% 17% 2	836
April	1st to 10th	Night	11% 5% 26% 38% 17% 3	646
	11th to 20th	Night	13% 4 26% 39% 16% 2	563
	21st to end	Night	15% 7% 22% 39% 17% 1	563
May	1st to 10th	Night	12% 7% 21% 38% 20% 3	380
	11th to 20th	Night	14% 5% 18% 40% 20% 3	374
	21st to end	Night	19% 4 18% 34% 22% 2	411
June	1st to 10th	Night	19% 4 18% 39% 17% 2	380
	11th to 20th	Night	19% 5% 14% 37% 22% 3	380
	21st to end	Night	11% 4 13% 43% 26% 4	380
July	1st to 10th	Night	13% 2 16% 39% 29%	370
	11th to 20th	Night	12% 4 18% 41% 23% 2	368
	21st to end	Night	10% 3 14% 40% 30% 4	416
August	1st to 10th	Night	9% 3 15% 37% 31% 6%	378
	11th to 20th	Night	12% 2 19% 40% 26% 1	457
	21st to end	Night	14% 3 17% 43% 22% 1	627
September	1st to 10th	Night	16% 3 21% 36% 23% 2	589
	11th to 20th	Night	15% 3 17% 43% 20% 1	760
	21st to end	Night	12% 4 29% 37% 16% 1	760
October	1st to 10th	Night	16% 4 26% 37% 17% 1	760
	11th to 20th	Night	14% 4 30% 37% 12% 3	760
	21st to end	Night	16% 7% 30% 34% 12% 1	880
November	1st to 10th	Night	17% 5% 30% 34% 11% 2	936
	11th to 20th	Night	14% 7% 34% 31% 11% 3	950
	21st to end	Night	11% 6% 37% 33% 12% 2	950
December	1st to 10th	Night	13% 7% 32% 32% 13% 3	950
	11th to 20th	Night	11% 7% 31% 36% 14% 2	950
	21st to end	Night	9% 4 30% 36% 18% 3	1139

Page generated at 2024-10-31 01:39:26. Version ac07

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