Chickadee Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chickadee Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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	17% 9% 4 7% 6% 3 5% 5% 5% 7% 33%	74741
	Night	17% 10% 4 7% 6% 3 4 4 5% 6% 33%	75036
Transparency	Day	50% 7% 11% 19% 11% 1	74446
	Night	51% 7% 11% 19% 10% 1	74865
Seeing	Day	23% 17% 31% 18% 8% 3	13368
	Night	22% 14% 31% 23% 8% 1	22653

By Month

Percentage Cloud Cover NE (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% 17% 7% 11% 6% 3 5% 4 4 5% 23%	1517
	11th to 20th	Day	19% 17% 7% 8% 6% 4 4 4 3 4 24%	1472
	21st to end	Day	14% 14% 6% 11% 10% 5% 5% 5% 4 4 24%	1710
February	1st to 10th	Day	16% 15% 5% 10% 7% 4 5% 5% 5% 6% 22%	1620
	11th to 20th	Day	13% 14% 6% 9% 7% 4 5% 4 4 5% 28%	1573
	21st to end	Day	21% 13% 6% 8% 8% 4 5% 4 4 5% 24%	1462
March	1st to 10th	Day	15% 11% 5% 11% 8% 4 5% 5% 3 4 30%	1837
	11th to 20th	Day	15% 13% 4 8% 7% 4 5% 5% 4 5% 31%	1980
	21st to end	Day	19% 11% 4 6% 4 3 3 3 4 4 38%	2265
April	1st to 10th	Day	21% 11% 4 6% 5% 3 3 3 5% 6% 33%	2160
	11th to 20th	Day	22% 8% 3 6% 4 3 4 4 4 5% 39%	2134
	21st to end	Day	22% 10% 3 6% 5% 3 4 4 5% 5% 32%	2262
May	1st to 10th	Day	19% 8% 3 7% 6% 3 4 4 5% 6% 35%	2520
	11th to 20th	Day	16% 7% 3 6% 6% 4 4 4 4 8% 39%	2478
	21st to end	Day	13% 6% 2 6% 6% 3 4 6% 6% 8% 39%	2725
June	1st to 10th	Day	21% 8% 4 6% 5% 3 5% 6% 6% 6% 31%	2520
	11th to 20th	Day	15% 6% 3 5% 4 3 6% 5% 6% 10% 37%	2520
	21st to end	Day	17% 7% 3 6% 6% 3 6% 5% 6% 8% 33%	2520
July	1st to 10th	Day	11% 4 3 6% 6% 4 5% 5% 6% 9% 41%	2520
	11th to 20th	Day	12% 6% 3 6% 5% 4 5% 5% 6% 10% 38%	2520
	21st to end	Day	12% 5% 3 5% 5% 4 7% 6% 8% 9% 36%	2744
August	1st to 10th	Day	12% 6% 2 6% 6% 4 5% 6% 6% 9% 38%	2405
	11th to 20th	Day	12% 6% 3 5% 6% 3 5% 6% 7% 9% 38%	2298
	21st to end	Day	14% 6% 2 6% 5% 3 5% 5% 6% 9% 39%	2376
September	1st to 10th	Day	14% 6% 3 5% 5% 3 5% 5% 5% 8% 41%	2160
	11th to 20th	Day	13% 5% 2 5% 5% 3 4 4 5% 7% 47%	2160
	21st to end	Day	18% 6% 2 6% 6% 3 4 5% 5% 7% 39%	1909
October	1st to 10th	Day	21% 9% 3 6% 5% 3 3 4 5% 6% 36%	1800
	11th to 20th	Day	21% 9% 3 7% 7% 4 5% 4 6% 7% 28%	1800
	21st to end	Day	26% 9% 4 7% 6% 4 5% 4 4 5% 25%	1878
November	1st to 10th	Day	15% 9% 3 7% 5% 3 6% 5% 6% 7% 34%	1658
	11th to 20th	Day	18% 12% 5% 7% 6% 3 5% 3 4 6% 29%	1520
	21st to end	Day	20% 15% 5% 9% 7% 4 5% 5% 4 4 22%	1520
December	1st to 10th	Day	22% 16% 5% 10% 7% 4 4 5% 4 6% 18%	1520
	11th to 20th	Day	21% 12% 6% 8% 7% 3 4 4 5% 4 25%	1906
	21st to end	Day	28% 16% 6% 12% 5% 3 3 2 2 3 20%	2772
January	1st to 10th	Night	18% 14% 7% 11% 8% 4 5% 4 5% 4 20%	2649
	11th to 20th	Night	17% 16% 6% 10% 8% 3 5% 4 4 5% 21%	2583
	21st to end	Night	13% 13% 6% 10% 7% 4 6% 4 4 4 28%	2646
February	1st to 10th	Night	14% 16% 5% 8% 8% 5% 4 5% 6% 6% 22%	2340
	11th to 20th	Night	13% 13% 6% 8% 6% 4 5% 4 4 6% 31%	2273
	21st to end	Night	15% 13% 5% 7% 7% 3 5% 5% 5% 6% 30%	1794
March	1st to 10th	Night	16% 12% 4 8% 7% 4 4 3 5% 5% 31%	2107
	11th to 20th	Night	17% 12% 5% 6% 5% 2 4 4 4 6% 34%	1979
	21st to end	Night	16% 9% 4 6% 6% 3 3 4 4 5% 40%	2090
April	1st to 10th	Night	20% 8% 4 7% 5% 3 4 4 4 6% 35%	1800
	11th to 20th	Night	19% 8% 3 6% 5% 3 5% 4 5% 5% 37%	1775
	21st to end	Night	20% 10% 4 7% 5% 3 4 4 5% 6% 32%	1714
May	1st to 10th	Night	21% 7% 3 5% 5% 3 4 5% 5% 5% 36%	1440
	11th to 20th	Night	15% 8% 2 5% 5% 2 4 4 5% 7% 43%	1415
	21st to end	Night	12% 5% 3 4 5% 3 4 5% 5% 9% 46%	1550
June	1st to 10th	Night	16% 7% 3 6% 6% 3 5% 6% 6% 8% 34%	1440
	11th to 20th	Night	14% 6% 3 5% 5% 3 5% 4 6% 8% 42%	1440
	21st to end	Night	16% 6% 3 6% 6% 4 6% 4 6% 9% 35%	1440
July	1st to 10th	Night	10% 5% 3 5% 5% 3 5% 4 6% 9% 46%	1440
	11th to 20th	Night	11% 6% 2 6% 5% 3 5% 4 6% 9% 44%	1440
	21st to end	Night	9% 5% 2 4 5% 3 5% 5% 6% 9% 47%	1574
August	1st to 10th	Night	10% 6% 2 6% 5% 4 5% 5% 6% 7% 44%	1529
	11th to 20th	Night	9% 6% 3 5% 6% 3 4 5% 6% 8% 44%	1598
	21st to end	Night	11% 6% 2 5% 6% 2 4 5% 6% 9% 45%	1966
September	1st to 10th	Night	12% 6% 2 5% 5% 3 4 4 5% 8% 45%	1800
	11th to 20th	Night	13% 4 2 4 4 2 4 4 5% 7% 50%	1800
	21st to end	Night	17% 6% 2 5% 4 3 4 4 4 6% 44%	2050
October	1st to 10th	Night	18% 7% 3 6% 5% 4 4 4 4 7% 37%	2160
	11th to 20th	Night	21% 9% 3 6% 6% 3 5% 4 5% 6% 31%	2160
	21st to end	Night	23% 10% 3 7% 6% 4 4 4 4 5% 29%	2476
November	1st to 10th	Night	18% 10% 3 6% 5% 3 4 5% 5% 6% 36%	2416
	11th to 20th	Night	18% 11% 3 6% 6% 3 5% 5% 5% 6% 32%	2660
	21st to end	Night	21% 12% 4 8% 6% 3 5% 4 5% 7% 24%	2660
December	1st to 10th	Night	20% 15% 6% 9% 8% 4 5% 5% 4 5% 19%	2660
	11th to 20th	Night	21% 15% 5% 8% 6% 3 4 3 4 4 28%	3288
	21st to end	Night	29% 16% 4 10% 6% 3 4 4 3 4 17%	4884

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	64% 6% 10% 14% 5% 1	1518
	11th to 20th	Day	64% 6% 8% 10% 11% 1	1472
	21st to end	Day	63% 6% 9% 13% 8% 2	1710
February	1st to 10th	Day	63% 6% 10% 15% 5% 1	1620
	11th to 20th	Day	59% 5% 11% 15% 9% 1	1582
	21st to end	Day	64% 4 9% 12% 10% 1	1462
March	1st to 10th	Day	59% 5% 10% 15% 9% 2	1840
	11th to 20th	Day	56% 7% 9% 15% 11% 2	1980
	21st to end	Day	50% 4 8% 19% 14% 6%	2265
April	1st to 10th	Day	54% 5% 8% 18% 12% 3	2160
	11th to 20th	Day	47% 6% 7% 22% 16% 2	2134
	21st to end	Day	54% 6% 9% 15% 14% 4	2262
May	1st to 10th	Day	50% 6% 10% 16% 15% 3	2520
	11th to 20th	Day	44% 7% 9% 22% 15% 3	2482
	21st to end	Day	42% 9% 14% 20% 13% 3	2725
June	1st to 10th	Day	51% 8% 10% 18% 12% 1	2520
	11th to 20th	Day	41% 8% 10% 25% 13% 2	2520
	21st to end	Day	48% 9% 13% 19% 11% 1	2520
July	1st to 10th	Day	38% 8% 12% 26% 14% 1	2450
	11th to 20th	Day	39% 10% 16% 25% 10%	2445
	21st to end	Day	41% 11% 15% 23% 10%	2591
August	1st to 10th	Day	41% 9% 14% 24% 11%	2391
	11th to 20th	Day	40% 10% 16% 23% 10% 1	2298
	21st to end	Day	39% 9% 14% 25% 12% 1	2376
September	1st to 10th	Day	39% 8% 15% 26% 12% 1	2160
	11th to 20th	Day	36% 8% 12% 29% 15%	2160
	21st to end	Day	44% 8% 13% 26% 9%	1909
October	1st to 10th	Day	49% 7% 11% 22% 11% 1	1800
	11th to 20th	Day	54% 9% 13% 17% 7% 1	1800
	21st to end	Day	59% 7% 10% 16% 7% 1	1878
November	1st to 10th	Day	47% 9% 16% 19% 8% 1	1658
	11th to 20th	Day	55% 7% 11% 15% 10% 1	1520
	21st to end	Day	62% 9% 11% 9% 7%	1520
December	1st to 10th	Day	67% 8% 11% 10% 4 1	1520
	11th to 20th	Day	62% 7% 14% 13% 4	1906
	21st to end	Day	71% 5% 7% 13% 4	2772
January	1st to 10th	Night	66% 6% 11% 12% 5%	2649
	11th to 20th	Night	65% 7% 9% 11% 8% 1	2583
	21st to end	Night	58% 6% 9% 16% 10% 1	2646
February	1st to 10th	Night	61% 7% 11% 15% 6% 1	2340
	11th to 20th	Night	55% 6% 11% 20% 8% 1	2275
	21st to end	Night	56% 6% 11% 16% 10% 1	1794
March	1st to 10th	Night	54% 5% 12% 17% 11% 1	2117
	11th to 20th	Night	52% 6% 11% 19% 11% 2	1980
	21st to end	Night	48% 5% 8% 20% 16% 4	2090
April	1st to 10th	Night	50% 5% 8% 21% 14% 2	1800
	11th to 20th	Night	49% 6% 7% 19% 17% 1	1775
	21st to end	Night	52% 5% 9% 15% 15% 3	1714
May	1st to 10th	Night	47% 6% 9% 18% 16% 4	1440
	11th to 20th	Night	40% 6% 11% 24% 16% 3	1416
	21st to end	Night	35% 8% 17% 18% 19% 3	1551
June	1st to 10th	Night	46% 9% 13% 20% 11% 1	1440
	11th to 20th	Night	39% 8% 12% 21% 18% 2	1440
	21st to end	Night	44% 10% 14% 19% 12% 1	1440
July	1st to 10th	Night	33% 9% 13% 25% 19% 3	1400
	11th to 20th	Night	36% 9% 13% 29% 13%	1392
	21st to end	Night	33% 8% 17% 28% 13% 1	1486
August	1st to 10th	Night	36% 8% 18% 25% 12% 1	1519
	11th to 20th	Night	36% 9% 17% 26% 12% 1	1598
	21st to end	Night	35% 9% 16% 28% 12% 1	1966
September	1st to 10th	Night	36% 9% 13% 27% 14% 1	1800
	11th to 20th	Night	32% 8% 15% 32% 12% 1	1800
	21st to end	Night	41% 7% 11% 31% 10% 1	2050
October	1st to 10th	Night	47% 7% 11% 20% 14%	2160
	11th to 20th	Night	53% 7% 14% 18% 8% 1	2160
	21st to end	Night	56% 8% 12% 15% 9%	2476
November	1st to 10th	Night	47% 7% 15% 20% 10% 1	2416
	11th to 20th	Night	52% 7% 11% 19% 10% 2	2660
	21st to end	Night	59% 8% 13% 15% 5%	2660
December	1st to 10th	Night	66% 7% 10% 13% 4	2660
	11th to 20th	Night	61% 6% 10% 15% 7% 1	3288
	21st to end	Night	71% 7% 8% 12% 3	4884

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	26% 22% 36% 13% 3 1	180
	11th to 20th	Day	36% 18% 27% 17% 2 1	168
	21st to end	Day	28% 21% 32% 15% 4	232
February	1st to 10th	Day	35% 27% 32% 5% 1	240
	11th to 20th	Day	29% 30% 38% 3	240
	21st to end	Day	35% 22% 31% 10% 2	328
March	1st to 10th	Day	25% 23% 34% 14% 4	420
	11th to 20th	Day	29% 22% 31% 13% 4	420
	21st to end	Day	32% 22% 26% 13% 6% 1	462
April	1st to 10th	Day	30% 24% 28% 12% 5%	420
	11th to 20th	Day	31% 22% 22% 15% 7% 3	412
	21st to end	Day	29% 22% 29% 12% 5% 2	420
May	1st to 10th	Day	26% 17% 31% 17% 6% 2	423
	11th to 20th	Day	19% 17% 35% 20% 7% 2	447
	21st to end	Day	18% 15% 34% 21% 9% 3	485
June	1st to 10th	Day	23% 12% 36% 21% 6% 2	450
	11th to 20th	Day	16% 17% 33% 21% 10% 2	450
	21st to end	Day	19% 16% 29% 24% 10% 3	450
July	1st to 10th	Day	14% 9% 29% 29% 16% 3	445
	11th to 20th	Day	15% 13% 31% 23% 15% 3	444
	21st to end	Day	13% 10% 36% 27% 10% 4	488
August	1st to 10th	Day	13% 9% 33% 29% 13% 4	446
	11th to 20th	Day	14% 8% 29% 27% 16% 6%	439
	21st to end	Day	14% 12% 33% 24% 11% 7%	495
September	1st to 10th	Day	14% 15% 31% 21% 12% 7%	450
	11th to 20th	Day	13% 10% 28% 23% 16% 10%	450
	21st to end	Day	19% 12% 30% 22% 13% 4	450
October	1st to 10th	Day	27% 17% 25% 16% 12% 4	450
	11th to 20th	Day	29% 20% 30% 15% 5% 1	450
	21st to end	Day	30% 21% 27% 18% 4	444
November	1st to 10th	Day	26% 18% 28% 20% 8%	352
	11th to 20th	Day	31% 21% 29% 13% 4 2	180
	21st to end	Day	30% 24% 28% 15% 3	180
December	1st to 10th	Day	32% 20% 34% 12% 2	180
	11th to 20th	Day	34% 23% 31% 9% 2 1	180
	21st to end	Day	33% 20% 32% 11% 3 1	198
January	1st to 10th	Night	28% 19% 31% 18% 4	760
	11th to 20th	Night	29% 17% 31% 18% 4 1	739
	21st to end	Night	19% 17% 37% 23% 4	792
February	1st to 10th	Night	24% 23% 34% 17% 2	720
	11th to 20th	Night	23% 21% 37% 17% 3	703
	21st to end	Night	24% 20% 36% 17% 3	592
March	1st to 10th	Night	25% 16% 36% 20% 3	720
	11th to 20th	Night	27% 20% 27% 21% 4 1	720
	21st to end	Night	22% 17% 33% 20% 7% 1	792
April	1st to 10th	Night	27% 17% 33% 21% 3	720
	11th to 20th	Night	24% 21% 29% 19% 7% 1	711
	21st to end	Night	25% 15% 29% 22% 8%	634
May	1st to 10th	Night	24% 11% 27% 26% 10% 2	360
	11th to 20th	Night	17% 10% 38% 28% 7%	354
	21st to end	Night	13% 9% 39% 26% 12% 1	389
June	1st to 10th	Night	16% 6% 36% 35% 7% 1	360
	11th to 20th	Night	14% 11% 33% 28% 13% 1	360
	21st to end	Night	16% 8% 29% 34% 12% 1	360
July	1st to 10th	Night	10% 6% 31% 37% 14% 1	350
	11th to 20th	Night	11% 4 33% 36% 15% 1	348
	21st to end	Night	11% 4 32% 41% 11% 1	394
August	1st to 10th	Night	12% 5% 28% 34% 20%	455
	11th to 20th	Night	11% 5% 24% 35% 22% 2	534
	21st to end	Night	12% 7% 32% 32% 15% 2	778
September	1st to 10th	Night	13% 8% 34% 27% 17% 2	720
	11th to 20th	Night	14% 9% 24% 28% 20% 4	720
	21st to end	Night	20% 11% 24% 26% 18% 2	720
October	1st to 10th	Night	22% 14% 28% 22% 13% 2	720
	11th to 20th	Night	27% 13% 32% 20% 7%	720
	21st to end	Night	30% 15% 28% 22% 5%	792
November	1st to 10th	Night	26% 14% 31% 21% 7%	740
	11th to 20th	Night	26% 17% 32% 16% 8% 1	760
	21st to end	Night	29% 19% 29% 19% 5%	760
December	1st to 10th	Night	29% 20% 31% 16% 3	760
	11th to 20th	Night	26% 19% 34% 17% 3 1	760
	21st to end	Night	34% 17% 30% 17% 1	836

Page generated at 2024-01-12 07:31:50. Version ac07

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