Chiloquin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chiloquin 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	6% 8% 2 5% 4 3 3 3 4 6% 54%	101489
	Night	7% 9% 2 6% 4 4 4 3 5% 6% 49%	97683
Transparency	Day	32% 5% 10% 20% 21% 13%	101235
	Night	36% 6% 11% 21% 17% 9%	97526
Seeing	Day	14% 12% 23% 24% 19% 8%	14844
	Night	11% 7% 16% 38% 26% 3	23905

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	11% 18% 6% 9% 7% 6% 5% 4 6% 6% 23%	2539
	11th to 20th	Day	17% 21% 5% 9% 5% 4 4 3 4 5% 23%	2572
	21st to end	Day	14% 15% 3 9% 6% 5% 5% 4 5% 6% 28%	3146
February	1st to 10th	Day	9% 12% 3 8% 4 6% 5% 4 7% 9% 33%	1710
	11th to 20th	Day	9% 14% 4 8% 5% 4 4 3 5% 7% 37%	1669
	21st to end	Day	6% 17% 4 8% 6% 5% 5% 4 6% 7% 32%	1570
March	1st to 10th	Day	9% 18% 5% 9% 6% 5% 5% 4 5% 5% 29%	3254
	11th to 20th	Day	7% 12% 3 5% 4 3 3 3 4 5% 51%	3490
	21st to end	Day	9% 18% 4 10% 7% 6% 5% 4 6% 7% 26%	3943
April	1st to 10th	Day	8% 14% 5% 9% 6% 4 5% 4 5% 6% 35%	2280
	11th to 20th	Day	8% 14% 4 6% 5% 4 4 3 6% 6% 40%	2249
	21st to end	Day	6% 9% 3 6% 4 4 4 3 5% 8% 47%	2323
May	1st to 10th	Day	7% 12% 2 5% 4 4 4 3 4 6% 51%	4285
	11th to 20th	Day	5% 5% 1 4 2 2 2 2 4 6% 66%	4377
	21st to end	Day	6% 6% 2 4 4 4 3 3 5% 7% 56%	4813
June	1st to 10th	Day	7% 7% 2 5% 5% 4 5% 4 6% 8% 48%	2660
	11th to 20th	Day	4 3 2 4 3 3 3 3 5% 7% 63%	2660
	21st to end	Day	4 2 1 3 2 2 3 2 3 5% 73%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 2 3 88%	4420
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 3 80%	4420
	21st to end	Day	1 1 1 1 1 1 1 2 3 87%	4708
August	1st to 10th	Day	3 2 1 2 2 2 3 2 4 5% 73%	4091
	11th to 20th	Day	1 1 1 2 2 2 2 2 3 4 80%	3995
	21st to end	Day	3 2 1 2 2 2 2 2 3 4 78%	4180
September	1st to 10th	Day	1 1 1 2 2 2 2 2 3 4 80%	2280
	11th to 20th	Day	4 3 2 4 3 3 3 4 5% 6% 64%	2280
	21st to end	Day	4 3 1 5% 3 3 3 2 4 6% 65%	2022
October	1st to 10th	Day	7% 5% 2 4 3 2 3 2 4 5% 63%	1900
	11th to 20th	Day	8% 5% 2 4 4 4 4 4 6% 7% 52%	1900
	21st to end	Day	9% 7% 2 7% 4 5% 3 3 4 8% 49%	2071
November	1st to 10th	Day	11% 10% 3 7% 5% 5% 5% 4 5% 7% 38%	1692
	11th to 20th	Day	10% 11% 3 7% 7% 6% 5% 5% 6% 8% 32%	1568
	21st to end	Day	7% 13% 3 7% 6% 5% 6% 4 6% 8% 35%	1520
December	1st to 10th	Day	8% 12% 4 7% 6% 5% 4 4 6% 8% 36%	1520
	11th to 20th	Day	13% 15% 3 9% 5% 6% 5% 4 6% 8% 26%	1928
	21st to end	Day	10% 16% 6% 13% 8% 6% 6% 4 4 5% 22%	2794
January	1st to 10th	Night	10% 16% 4 9% 7% 7% 6% 5% 6% 7% 22%	4406
	11th to 20th	Night	13% 17% 5% 9% 6% 5% 5% 3 4 6% 25%	4386
	21st to end	Night	16% 16% 5% 9% 6% 6% 6% 4 5% 6% 22%	4521
February	1st to 10th	Night	8% 10% 3 7% 6% 5% 6% 5% 8% 8% 36%	2470
	11th to 20th	Night	7% 13% 3 7% 6% 5% 6% 4 5% 6% 39%	2397
	21st to end	Night	6% 14% 4 7% 5% 4 5% 5% 7% 8% 36%	1884
March	1st to 10th	Night	7% 16% 4 8% 5% 5% 5% 5% 7% 7% 30%	3617
	11th to 20th	Night	6% 12% 3 5% 4 3 4 2 4 5% 52%	3490
	21st to end	Night	6% 15% 4 9% 6% 6% 7% 5% 7% 7% 27%	3710
April	1st to 10th	Night	9% 12% 3 8% 5% 5% 4 4 5% 7% 38%	1900
	11th to 20th	Night	6% 10% 4 6% 6% 4 3 3 5% 7% 46%	1879
	21st to end	Night	7% 8% 2 5% 3 4 4 4 6% 8% 48%	1853
May	1st to 10th	Night	9% 11% 2 4 3 3 3 2 4 5% 54%	2678
	11th to 20th	Night	3 4 1 4 3 3 3 2 4 5% 69%	2516
	21st to end	Night	5% 5% 1 4 2 2 3 2 4 6% 65%	2762
June	1st to 10th	Night	8% 7% 2 4 4 4 4 3 5% 7% 51%	1520
	11th to 20th	Night	5% 4 1 3 2 2 3 3 4 6% 67%	1520
	21st to end	Night	4 3 1 3 2 2 2 2 3 4 75%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 2 3 88%	2540
	11th to 20th	Night	1 1 1 1 2 2 2 2 3 4 81%	2540
	21st to end	Night	1 1 2 1 1 2 2 3 3 83%	2843
August	1st to 10th	Night	2 2 1 2 2 2 3 3 5% 5% 73%	2848
	11th to 20th	Night	1 1 1 2 2 2 2 2 3 5% 79%	2844
	21st to end	Night	4 2 1 2 1 1 2 2 3 4 79%	3498
September	1st to 10th	Night	1 1 1 1 1 1 2 3 5% 82%	1900
	11th to 20th	Night	3 3 1 2 2 2 3 3 4 7% 70%	1900
	21st to end	Night	6% 4 1 3 2 2 2 2 3 5% 69%	2154
October	1st to 10th	Night	5% 4 1 3 3 2 3 3 4 7% 66%	2280
	11th to 20th	Night	8% 5% 1 5% 3 3 3 3 4 7% 58%	2280
	21st to end	Night	8% 6% 2 5% 4 4 5% 3 6% 7% 50%	2527
November	1st to 10th	Night	12% 10% 2 6% 5% 5% 5% 4 6% 7% 39%	2431
	11th to 20th	Night	12% 9% 2 7% 5% 6% 6% 5% 6% 8% 33%	2611
	21st to end	Night	8% 11% 3 6% 5% 4 5% 4 5% 8% 40%	2660
December	1st to 10th	Night	10% 10% 4 7% 5% 4 3 3 7% 8% 40%	2660
	11th to 20th	Night	11% 14% 5% 9% 6% 5% 6% 4 7% 7% 27%	3276
	21st to end	Night	11% 14% 4 11% 7% 7% 5% 4 5% 6% 25%	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	60% 8% 14% 14% 4	2539
	11th to 20th	Day	64% 6% 8% 13% 5% 3	2572
	21st to end	Day	56% 8% 12% 16% 6% 2	3146
February	1st to 10th	Day	46% 8% 15% 19% 10% 1	1710
	11th to 20th	Day	48% 6% 14% 18% 12% 2	1678
	21st to end	Day	52% 6% 13% 15% 12% 3	1570
March	1st to 10th	Day	55% 5% 13% 17% 9% 1	3254
	11th to 20th	Day	36% 5% 12% 24% 23% 1	3490
	21st to end	Day	54% 8% 13% 18% 6% 1	3943
April	1st to 10th	Day	51% 6% 11% 18% 11% 3	2280
	11th to 20th	Day	44% 6% 14% 20% 13% 4	2252
	21st to end	Day	35% 7% 15% 25% 15% 2	2323
May	1st to 10th	Day	33% 4 12% 26% 22% 2	4285
	11th to 20th	Day	21% 3 8% 22% 38% 8%	4380
	21st to end	Day	27% 6% 15% 36% 15% 2	4814
June	1st to 10th	Day	34% 6% 14% 26% 19% 1	2660
	11th to 20th	Day	21% 5% 10% 30% 27% 7%	2660
	21st to end	Day	17% 3 7% 25% 32% 16%	2660
July	1st to 10th	Day	6% 1 4 12% 19% 58%	4351
	11th to 20th	Day	12% 3 3 10% 21% 52%	4345
	21st to end	Day	6% 1 3 13% 39% 37%	4559
August	1st to 10th	Day	15% 3 4 13% 30% 35%	4076
	11th to 20th	Day	9% 2 4 24% 42% 19%	4034
	21st to end	Day	12% 2 5% 26% 31% 23%	4179
September	1st to 10th	Day	10% 2 5% 17% 34% 32%	2280
	11th to 20th	Day	21% 4 8% 22% 30% 15%	2280
	21st to end	Day	22% 2 9% 23% 28% 16%	2022
October	1st to 10th	Day	26% 4 11% 18% 27% 15%	1900
	11th to 20th	Day	30% 6% 13% 23% 21% 8%	1900
	21st to end	Day	37% 6% 10% 21% 20% 7%	2071
November	1st to 10th	Day	45% 7% 11% 20% 14% 3	1692
	11th to 20th	Day	48% 8% 16% 14% 13% 1	1568
	21st to end	Day	47% 6% 14% 15% 15% 3	1520
December	1st to 10th	Day	45% 8% 14% 20% 12% 2	1520
	11th to 20th	Day	56% 9% 14% 14% 6% 1	1928
	21st to end	Day	63% 8% 10% 13% 5%	2794
January	1st to 10th	Night	56% 11% 14% 12% 5% 1	4406
	11th to 20th	Night	57% 9% 10% 14% 6% 4	4386
	21st to end	Night	60% 7% 11% 13% 8% 1	4521
February	1st to 10th	Night	44% 7% 15% 19% 12% 2	2470
	11th to 20th	Night	46% 6% 14% 20% 12% 2	2399
	21st to end	Night	46% 8% 15% 18% 10% 3	1884
March	1st to 10th	Night	49% 7% 15% 20% 9% 1	3617
	11th to 20th	Night	35% 5% 12% 28% 19%	3490
	21st to end	Night	52% 12% 13% 15% 7% 1	3710
April	1st to 10th	Night	46% 7% 16% 19% 10% 1	1900
	11th to 20th	Night	40% 6% 17% 22% 12% 4	1879
	21st to end	Night	35% 8% 17% 25% 12% 2	1853
May	1st to 10th	Night	32% 5% 12% 30% 18% 3	2678
	11th to 20th	Night	19% 4 9% 31% 34% 2	2516
	21st to end	Night	21% 5% 22% 42% 9% 1	2762
June	1st to 10th	Night	34% 6% 15% 28% 16% 1	1520
	11th to 20th	Night	19% 5% 13% 34% 23% 6%	1520
	21st to end	Night	15% 3 9% 33% 31% 10%	1520
July	1st to 10th	Night	6% 1 6% 15% 20% 53%	2500
	11th to 20th	Night	10% 2 3 12% 29% 44%	2492
	21st to end	Night	10% 2 4 13% 40% 31%	2754
August	1st to 10th	Night	14% 3 6% 16% 35% 26%	2839
	11th to 20th	Night	10% 3 4 33% 33% 17%	2871
	21st to end	Night	13% 2 7% 29% 26% 22%	3498
September	1st to 10th	Night	7% 2 4 21% 35% 31%	1900
	11th to 20th	Night	16% 4 10% 26% 28% 16%	1900
	21st to end	Night	20% 3 8% 26% 25% 19%	2154
October	1st to 10th	Night	21% 4 12% 19% 28% 15%	2280
	11th to 20th	Night	29% 4 12% 24% 22% 9%	2280
	21st to end	Night	33% 7% 12% 21% 18% 9%	2527
November	1st to 10th	Night	45% 5% 12% 18% 15% 4	2431
	11th to 20th	Night	47% 8% 13% 18% 13% 1	2611
	21st to end	Night	42% 7% 14% 18% 15% 4	2660
December	1st to 10th	Night	42% 8% 12% 21% 15% 2	2660
	11th to 20th	Night	56% 8% 11% 17% 8% 1	3276
	21st to end	Night	56% 9% 10% 15% 7% 1	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	28% 13% 24% 20% 12% 3	180
	11th to 20th	Day	30% 7% 22% 23% 13% 6%	199
	21st to end	Day	19% 13% 23% 17% 19% 9%	407
February	1st to 10th	Day	19% 15% 24% 23% 14% 5%	370
	11th to 20th	Day	24% 19% 20% 17% 14% 5%	367
	21st to end	Day	23% 15% 25% 23% 11% 3	382
March	1st to 10th	Day	28% 18% 23% 22% 8% 2	460
	11th to 20th	Day	22% 16% 23% 21% 14% 4	460
	21st to end	Day	26% 20% 24% 21% 7% 3	506
April	1st to 10th	Day	22% 17% 27% 18% 13% 4	460
	11th to 20th	Day	22% 20% 24% 21% 9% 4	452
	21st to end	Day	17% 19% 25% 20% 15% 4	460
May	1st to 10th	Day	16% 16% 29% 23% 12% 5%	463
	11th to 20th	Day	19% 14% 23% 21% 17% 6%	488
	21st to end	Day	16% 11% 21% 23% 19% 10%	529
June	1st to 10th	Day	12% 16% 24% 20% 20% 8%	490
	11th to 20th	Day	12% 17% 25% 24% 18% 5%	490
	21st to end	Day	4 10% 24% 27% 27% 10%	490
July	1st to 10th	Day	2 8% 27% 31% 22% 10%	486
	11th to 20th	Day	1 7% 27% 30% 25% 10%	484
	21st to end	Day	3 6% 21% 29% 30% 12%	531
August	1st to 10th	Day	2 4 25% 29% 27% 14%	487
	11th to 20th	Day	4 6% 19% 30% 22% 20%	477
	21st to end	Day	4 5% 20% 27% 29% 14%	539
September	1st to 10th	Day	2 5% 21% 28% 29% 14%	490
	11th to 20th	Day	8% 8% 20% 28% 24% 12%	490
	21st to end	Day	8% 11% 21% 28% 23% 10%	490
October	1st to 10th	Day	11% 11% 21% 22% 21% 13%	490
	11th to 20th	Day	17% 9% 17% 20% 25% 12%	490
	21st to end	Day	18% 10% 22% 21% 16% 13%	520
November	1st to 10th	Day	19% 11% 18% 29% 15% 8%	276
	11th to 20th	Day	15% 8% 20% 23% 25% 9%	203
	21st to end	Day	17% 13% 14% 23% 25% 8%	180
December	1st to 10th	Day	22% 11% 17% 24% 16% 10%	180
	11th to 20th	Day	27% 12% 18% 22% 15% 6%	180
	21st to end	Day	26% 10% 21% 25% 16% 3	198
January	1st to 10th	Night	18% 10% 19% 34% 16% 3	760
	11th to 20th	Night	15% 10% 19% 34% 21% 3	760
	21st to end	Night	15% 8% 17% 36% 21% 3	836
February	1st to 10th	Night	13% 8% 20% 38% 19% 1	760
	11th to 20th	Night	13% 10% 21% 35% 19% 1	744
	21st to end	Night	13% 12% 21% 38% 16%	628
March	1st to 10th	Night	18% 12% 21% 33% 15% 2	760
	11th to 20th	Night	14% 10% 18% 34% 22% 1	760
	21st to end	Night	15% 13% 22% 35% 15%	836
April	1st to 10th	Night	16% 11% 19% 37% 16% 2	760
	11th to 20th	Night	9% 13% 26% 31% 18% 3	751
	21st to end	Night	11% 10% 20% 35% 22% 2	713
May	1st to 10th	Night	11% 5% 22% 38% 22% 2	466
	11th to 20th	Night	8% 7% 16% 34% 33% 3	374
	21st to end	Night	10% 6% 17% 37% 27% 3	411
June	1st to 10th	Night	12% 4 13% 39% 31% 1	380
	11th to 20th	Night	6% 4 17% 51% 22%	380
	21st to end	Night	5% 1 9% 47% 37%	380
July	1st to 10th	Night	2 1 8% 45% 44% 1	370
	11th to 20th	Night	1 7% 56% 35%	368
	21st to end	Night	2 1 3 48% 44% 3	462
August	1st to 10th	Night	2 3 42% 48% 5%	567
	11th to 20th	Night	1 1 5% 37% 51% 6%	583
	21st to end	Night	3 2 12% 42% 39% 2	836
September	1st to 10th	Night	2 2 12% 40% 41% 3	760
	11th to 20th	Night	4 4 12% 36% 39% 6%	760
	21st to end	Night	7% 3 13% 39% 33% 6%	760
October	1st to 10th	Night	7% 5% 15% 38% 32% 4	760
	11th to 20th	Night	11% 5% 12% 36% 32% 4	760
	21st to end	Night	13% 6% 14% 37% 25% 6%	836
November	1st to 10th	Night	16% 5% 17% 39% 20% 3	748
	11th to 20th	Night	15% 8% 18% 39% 18% 2	760
	21st to end	Night	13% 10% 18% 35% 22% 3	760
December	1st to 10th	Night	16% 8% 16% 35% 20% 4	760
	11th to 20th	Night	18% 9% 16% 37% 19% 2	760
	21st to end	Night	20% 13% 21% 34% 11% 1	836

Page generated at 2024-10-31 00:39:22. Version ac07

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