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 2024-03-18.

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	7% 8% 3 5% 5% 3 4 4 5% 6% 50%	78685
	Night	8% 9% 3 5% 5% 3 5% 5% 5% 7% 45%	81134
Transparency	Day	36% 5% 11% 20% 19% 9%	78391
	Night	39% 6% 12% 20% 16% 7%	80949
Seeing	Day	14% 12% 23% 24% 19% 8%	13928
	Night	11% 7% 16% 37% 26% 3	23188

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	12% 18% 6% 7% 7% 4 6% 5% 6% 6% 23%	2539
	11th to 20th	Day	17% 20% 5% 8% 6% 4 4 4 4 5% 23%	2572
	21st to end	Day	14% 15% 3 7% 8% 4 5% 5% 5% 6% 28%	3146
February	1st to 10th	Day	9% 12% 3 6% 5% 4 6% 5% 7% 9% 33%	1710
	11th to 20th	Day	9% 13% 5% 7% 6% 3 4 4 5% 7% 37%	1669
	21st to end	Day	6% 15% 5% 8% 7% 4 5% 5% 6% 7% 32%	1570
March	1st to 10th	Day	10% 15% 6% 8% 7% 4 4 4 5% 6% 29%	1968
	11th to 20th	Day	10% 14% 4 7% 6% 3 5% 5% 5% 6% 35%	2059
	21st to end	Day	10% 15% 5% 8% 8% 3 5% 6% 6% 7% 29%	2245
April	1st to 10th	Day	8% 13% 5% 9% 7% 3 5% 5% 5% 6% 33%	2160
	11th to 20th	Day	8% 13% 5% 6% 5% 3 4 4 5% 6% 40%	2129
	21st to end	Day	6% 9% 3 5% 5% 3 4 5% 5% 8% 47%	2200
May	1st to 10th	Day	6% 6% 3 5% 5% 3 4 3 5% 7% 52%	2437
	11th to 20th	Day	9% 8% 3 5% 4 3 4 4 5% 8% 47%	2477
	21st to end	Day	10% 7% 3 6% 5% 4 5% 5% 5% 7% 44%	2723
June	1st to 10th	Day	8% 6% 2 5% 5% 3 4 5% 5% 8% 49%	2520
	11th to 20th	Day	4 3 2 4 4 2 3 4 5% 6% 63%	2520
	21st to end	Day	4 2 1 3 2 2 3 2 3 6% 72%	2520
July	1st to 10th	Day	2 1 1 2 2 1 2 3 4 5% 79%	2520
	11th to 20th	Day	1 1 1 2 2 1 2 2 3 4 82%	2520
	21st to end	Day	2 1 1 1 2 1 2 2 3 3 82%	2695
August	1st to 10th	Day	2 1 1 2 2 2 3 3 4 6% 74%	2328
	11th to 20th	Day	3 1 1 2 2 1 2 2 3 4 80%	2280
	21st to end	Day	2 2 1 2 1 1 1 2 3 4 82%	2376
September	1st to 10th	Day	1 1 1 2 2 1 2 2 3 5% 80%	2160
	11th to 20th	Day	4 2 2 4 3 2 3 4 5% 6% 64%	2160
	21st to end	Day	4 4 1 4 5% 2 3 3 4 6% 64%	1916
October	1st to 10th	Day	7% 5% 2 4 3 2 3 3 4 5% 62%	1800
	11th to 20th	Day	9% 5% 2 3 5% 3 4 5% 6% 6% 53%	1800
	21st to end	Day	9% 7% 2 6% 5% 3 4 3 4 7% 50%	1962
November	1st to 10th	Day	11% 9% 3 6% 6% 3 5% 5% 5% 7% 39%	1674
	11th to 20th	Day	10% 10% 3 6% 7% 4 5% 7% 6% 7% 33%	1568
	21st to end	Day	7% 11% 4 6% 7% 4 5% 6% 6% 8% 35%	1520
December	1st to 10th	Day	8% 11% 4 6% 6% 4 5% 4 6% 8% 37%	1520
	11th to 20th	Day	14% 14% 4 8% 6% 4 6% 5% 5% 8% 26%	1928
	21st to end	Day	10% 15% 6% 11% 10% 4 6% 5% 4 6% 22%	2794
January	1st to 10th	Night	11% 16% 4 8% 8% 5% 7% 6% 7% 7% 22%	4406
	11th to 20th	Night	13% 16% 5% 8% 8% 4 5% 4 4 6% 25%	4386
	21st to end	Night	16% 16% 5% 8% 7% 5% 6% 5% 4 6% 23%	4521
February	1st to 10th	Night	8% 9% 3 6% 7% 4 6% 6% 7% 9% 36%	2470
	11th to 20th	Night	7% 12% 4 6% 6% 4 6% 6% 5% 6% 39%	2397
	21st to end	Night	6% 12% 4 7% 6% 3 6% 6% 7% 8% 36%	1884
March	1st to 10th	Night	9% 12% 5% 8% 6% 3 5% 6% 7% 7% 32%	2209
	11th to 20th	Night	7% 13% 4 6% 6% 4 5% 5% 5% 7% 37%	2067
	21st to end	Night	7% 13% 4 7% 6% 4 6% 7% 6% 7% 32%	2111
April	1st to 10th	Night	10% 10% 4 8% 6% 4 5% 5% 5% 7% 37%	1800
	11th to 20th	Night	6% 9% 5% 6% 6% 3 4 4 5% 7% 45%	1779
	21st to end	Night	7% 7% 2 4 4 3 4 4 6% 8% 49%	1756
May	1st to 10th	Night	5% 7% 1 4 5% 3 4 3 5% 8% 55%	1522
	11th to 20th	Night	6% 7% 1 5% 5% 3 6% 5% 7% 8% 47%	1416
	21st to end	Night	7% 7% 2 5% 4 2 5% 5% 5% 8% 50%	1552
June	1st to 10th	Night	9% 7% 2 4 4 3 5% 4 5% 7% 51%	1440
	11th to 20th	Night	5% 3 1 3 2 2 3 4 4 6% 66%	1440
	21st to end	Night	4 3 1 2 3 2 2 2 3 4 75%	1440
July	1st to 10th	Night	2 1 1 1 2 1 3 2 4 6% 79%	1440
	11th to 20th	Night	1 1 1 1 1 1 2 2 3 4 83%	1440
	21st to end	Night	1 1 1 2 1 1 2 2 3 4 81%	1619
August	1st to 10th	Night	1 1 2 2 2 3 5% 6% 5% 73%	1611
	11th to 20th	Night	1 1 1 2 2 1 3 3 3 4 79%	1620
	21st to end	Night	2 1 1 2 2 1 2 3 3 4 81%	1980
September	1st to 10th	Night	1 1 1 1 1 1 2 2 3 5% 82%	1800
	11th to 20th	Night	3 2 1 2 2 2 2 3 4 7% 71%	1800
	21st to end	Night	7% 4 1 3 2 2 2 3 3 6% 68%	2040
October	1st to 10th	Night	5% 4 1 3 3 2 3 3 4 7% 65%	2160
	11th to 20th	Night	8% 5% 2 4 3 3 3 4 4 7% 58%	2160
	21st to end	Night	9% 5% 2 5% 5% 3 4 4 6% 6% 51%	2394
November	1st to 10th	Night	12% 9% 2 6% 6% 3 5% 5% 5% 7% 40%	2405
	11th to 20th	Night	12% 8% 3 6% 6% 4 6% 7% 6% 8% 33%	2611
	21st to end	Night	8% 10% 4 5% 6% 3 5% 5% 6% 8% 40%	2660
December	1st to 10th	Night	10% 10% 4 5% 6% 4 3 4 6% 7% 40%	2660
	11th to 20th	Night	11% 13% 5% 8% 8% 4 6% 5% 6% 7% 27%	3276
	21st to end	Night	11% 14% 5% 9% 8% 6% 6% 5% 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	56% 6% 14% 17% 7% 1	1968
	11th to 20th	Day	49% 6% 12% 19% 13% 1	2059
	21st to end	Day	54% 8% 16% 14% 8% 1	2245
April	1st to 10th	Day	53% 6% 11% 17% 10% 3	2160
	11th to 20th	Day	44% 6% 14% 19% 13% 4	2132
	21st to end	Day	35% 7% 15% 25% 15% 3	2200
May	1st to 10th	Day	31% 5% 13% 30% 19% 2	2437
	11th to 20th	Day	37% 5% 12% 26% 16% 4	2480
	21st to end	Day	39% 6% 14% 26% 13% 2	2724
June	1st to 10th	Day	34% 6% 13% 27% 19% 1	2520
	11th to 20th	Day	21% 5% 10% 31% 26% 6%	2520
	21st to end	Day	17% 3 7% 26% 32% 16%	2520
July	1st to 10th	Day	11% 2 8% 21% 30% 28%	2451
	11th to 20th	Day	9% 3 5% 18% 31% 35%	2445
	21st to end	Day	10% 2 4 13% 36% 34%	2545
August	1st to 10th	Day	12% 4 7% 22% 33% 22%	2312
	11th to 20th	Day	11% 2 6% 18% 40% 24%	2280
	21st to end	Day	9% 2 5% 19% 41% 24%	2376
September	1st to 10th	Day	10% 2 5% 17% 34% 32%	2160
	11th to 20th	Day	21% 4 8% 21% 31% 16%	2160
	21st to end	Day	23% 2 9% 23% 27% 15%	1916
October	1st to 10th	Day	27% 4 11% 18% 26% 14%	1800
	11th to 20th	Day	31% 6% 12% 23% 21% 8%	1800
	21st to end	Day	37% 6% 10% 21% 20% 7%	1962
November	1st to 10th	Day	44% 7% 12% 20% 14% 3	1674
	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	50% 7% 14% 18% 11% 1	2209
	11th to 20th	Night	47% 6% 14% 19% 15%	2067
	21st to end	Night	50% 9% 15% 17% 7% 1	2111
April	1st to 10th	Night	48% 7% 15% 19% 10% 1	1800
	11th to 20th	Night	41% 6% 16% 20% 12% 4	1779
	21st to end	Night	35% 7% 17% 26% 12% 2	1756
May	1st to 10th	Night	29% 6% 13% 33% 17% 2	1522
	11th to 20th	Night	33% 8% 16% 30% 11% 2	1416
	21st to end	Night	33% 6% 22% 27% 10% 1	1552
June	1st to 10th	Night	34% 7% 15% 27% 16% 1	1440
	11th to 20th	Night	20% 5% 13% 35% 22% 5%	1440
	21st to end	Night	16% 3 9% 32% 31% 9%	1440
July	1st to 10th	Night	10% 2 10% 26% 28% 23%	1400
	11th to 20th	Night	9% 2 6% 20% 36% 28%	1392
	21st to end	Night	11% 2 4 14% 41% 28%	1529
August	1st to 10th	Night	12% 4 10% 27% 30% 16%	1602
	11th to 20th	Night	10% 4 6% 25% 36% 20%	1620
	21st to end	Night	9% 2 6% 23% 37% 22%	1980
September	1st to 10th	Night	7% 2 4 22% 34% 31%	1800
	11th to 20th	Night	15% 4 10% 24% 29% 17%	1800
	21st to end	Night	21% 3 8% 25% 24% 19%	2040
October	1st to 10th	Night	22% 5% 13% 20% 28% 13%	2160
	11th to 20th	Night	29% 4 12% 23% 23% 9%	2160
	21st to end	Night	33% 7% 12% 21% 18% 9%	2394
November	1st to 10th	Night	45% 5% 12% 18% 16% 4	2405
	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	23% 16% 23% 21% 13% 3	449
	21st to end	Day	27% 19% 22% 21% 8% 3	462
April	1st to 10th	Day	23% 17% 27% 17% 12% 4	420
	11th to 20th	Day	23% 21% 24% 19% 9% 4	412
	21st to end	Day	16% 20% 26% 19% 15% 5%	420
May	1st to 10th	Day	14% 15% 30% 23% 13% 5%	423
	11th to 20th	Day	21% 15% 23% 20% 16% 6%	448
	21st to end	Day	17% 11% 21% 22% 19% 9%	485
June	1st to 10th	Day	11% 17% 25% 19% 20% 8%	450
	11th to 20th	Day	12% 18% 25% 24% 17% 5%	450
	21st to end	Day	4 9% 24% 27% 26% 10%	450
July	1st to 10th	Day	2 9% 28% 31% 21% 8%	446
	11th to 20th	Day	1 7% 27% 30% 24% 11%	444
	21st to end	Day	3 5% 21% 29% 30% 12%	487
August	1st to 10th	Day	2 4 25% 30% 26% 14%	447
	11th to 20th	Day	4 5% 18% 29% 23% 22%	437
	21st to end	Day	4 5% 21% 28% 29% 13%	495
September	1st to 10th	Day	2 5% 22% 29% 28% 14%	450
	11th to 20th	Day	8% 8% 20% 27% 25% 12%	450
	21st to end	Day	8% 11% 21% 27% 23% 9%	450
October	1st to 10th	Day	12% 12% 22% 22% 21% 12%	450
	11th to 20th	Day	17% 9% 18% 19% 24% 13%	450
	21st to end	Day	17% 11% 22% 20% 17% 14%	477
November	1st to 10th	Day	19% 10% 18% 30% 15% 9%	270
	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% 19% 34% 22% 1	752
	21st to end	Night	15% 13% 21% 35% 15%	792
April	1st to 10th	Night	16% 11% 19% 36% 16% 2	720
	11th to 20th	Night	9% 14% 26% 31% 18% 3	711
	21st to end	Night	10% 10% 20% 34% 23% 3	676
May	1st to 10th	Night	10% 5% 21% 39% 23% 2	442
	11th to 20th	Night	8% 7% 15% 34% 32% 3	354
	21st to end	Night	11% 6% 16% 37% 28% 3	389
June	1st to 10th	Night	13% 4 14% 38% 31% 1	360
	11th to 20th	Night	6% 4 17% 50% 23%	360
	21st to end	Night	5% 1 10% 46% 37%	360
July	1st to 10th	Night	2 1 8% 45% 43% 1	350
	11th to 20th	Night	1 7% 57% 34%	348
	21st to end	Night	1 1 3 47% 45% 3	437
August	1st to 10th	Night	1 3 41% 48% 5%	537
	11th to 20th	Night	1 5% 36% 52% 6%	552
	21st to end	Night	2 2 12% 42% 39% 2	792
September	1st to 10th	Night	2 2 12% 40% 41% 3	720
	11th to 20th	Night	3 4 11% 35% 40% 6%	720
	21st to end	Night	8% 3 13% 38% 32% 6%	720
October	1st to 10th	Night	7% 5% 15% 37% 32% 4	720
	11th to 20th	Night	10% 5% 13% 35% 32% 5%	720
	21st to end	Night	13% 6% 14% 36% 26% 6%	792
November	1st to 10th	Night	15% 5% 17% 40% 20% 3	740
	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 2024-03-15 11:01:43. Version ac07

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