Wild Rose Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wild Rose Ridge Observatory clear sky chart from 2005-11-06 to 2026-07-16.

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	5% 6% 2 6% 4 4 5% 4 6% 7% 50%	142192
	Night	5% 8% 3 7% 4 4 4 4 6% 7% 47%	139221
Transparency	Day	33% 7% 13% 25% 17% 5%	141920
	Night	36% 7% 15% 25% 13% 3	139075
Seeing	Day	12% 16% 32% 28% 11% 2	16417
	Night	10% 9% 31% 33% 14% 2	25369

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	6% 15% 5% 10% 7% 7% 7% 5% 7% 7% 25%	4723
	11th to 20th	Day	4 10% 4 7% 4 4 4 4 5% 6% 46%	4716
	21st to end	Day	9% 12% 4 9% 6% 5% 5% 4 7% 7% 33%	5186
February	1st to 10th	Day	6% 10% 3 10% 6% 6% 6% 5% 7% 8% 32%	1848
	11th to 20th	Day	5% 11% 4 9% 5% 6% 4 4 7% 8% 36%	1845
	21st to end	Day	5% 11% 4 10% 7% 5% 6% 6% 7% 7% 33%	1710
March	1st to 10th	Day	3 8% 2 7% 5% 6% 7% 5% 9% 10% 38%	4618
	11th to 20th	Day	4 9% 3 8% 5% 6% 5% 4 6% 7% 44%	5006
	21st to end	Day	9% 9% 4 9% 6% 6% 6% 5% 7% 9% 30%	5956
April	1st to 10th	Day	7% 8% 3 7% 7% 5% 7% 5% 9% 7% 34%	2520
	11th to 20th	Day	5% 7% 2 6% 6% 5% 6% 4 7% 10% 43%	2492
	21st to end	Day	5% 5% 3 6% 4 5% 5% 4 8% 9% 46%	2782
May	1st to 10th	Day	4 4 1 5% 3 4 5% 4 5% 7% 58%	8195
	11th to 20th	Day	4 4 2 5% 4 4 4 4 6% 9% 54%	8160
	21st to end	Day	6% 6% 3 6% 5% 5% 5% 4 6% 8% 47%	8993
June	1st to 10th	Day	7% 6% 2 5% 5% 5% 6% 4 7% 8% 46%	2940
	11th to 20th	Day	4 4 2 5% 4 4 4 4 6% 9% 53%	2940
	21st to end	Day	4 3 1 5% 4 4 4 3 5% 7% 59%	2940
July	1st to 10th	Day	1 2 1 2 1 2 2 2 3 4 80%	6460
	11th to 20th	Day	1 1 1 2 2 2 2 2 3 4 80%	6391
	21st to end	Day	2 2 1 3 2 2 2 2 3 6% 74%	6874
August	1st to 10th	Day	1 2 1 2 2 3 3 3 5% 6% 73%	4541
	11th to 20th	Day	1 1 1 3 3 3 5% 4 5% 8% 65%	4251
	21st to end	Day	4 5% 2 4 3 3 3 3 4 6% 62%	4348
September	1st to 10th	Day	3 2 1 3 2 2 3 3 5% 7% 69%	2400
	11th to 20th	Day	3 4 2 4 3 4 5% 4 6% 8% 56%	2400
	21st to end	Day	5% 3 2 5% 4 4 5% 4 5% 7% 57%	2151
October	1st to 10th	Day	3 3 2 6% 4 3 3 3 5% 8% 60%	3280
	11th to 20th	Day	5% 6% 2 7% 5% 5% 6% 5% 7% 9% 44%	3261
	21st to end	Day	6% 7% 3 7% 4 5% 6% 5% 6% 8% 43%	3217
November	1st to 10th	Day	8% 11% 3 7% 5% 6% 5% 4 7% 8% 36%	1791
	11th to 20th	Day	6% 12% 3 11% 7% 6% 6% 5% 6% 7% 31%	1680
	21st to end	Day	5% 13% 4 10% 6% 5% 5% 5% 7% 8% 31%	1680
December	1st to 10th	Day	4 9% 3 9% 5% 5% 5% 4 9% 7% 38%	2700
	11th to 20th	Day	7% 16% 6% 14% 8% 7% 5% 4 6% 7% 20%	3105
	21st to end	Day	9% 17% 6% 14% 6% 6% 5% 4 5% 6% 23%	4092
January	1st to 10th	Night	8% 17% 6% 14% 6% 5% 4 4 5% 6% 24%	8172
	11th to 20th	Night	5% 9% 4 7% 5% 5% 5% 4 6% 8% 43%	8182
	21st to end	Night	7% 13% 4 12% 6% 5% 5% 4 6% 7% 31%	8994
February	1st to 10th	Night	6% 12% 3 9% 6% 5% 5% 5% 7% 8% 32%	2770
	11th to 20th	Night	6% 10% 3 8% 5% 5% 5% 5% 6% 7% 40%	2662
	21st to end	Night	5% 10% 3 10% 5% 5% 5% 5% 7% 8% 36%	2095
March	1st to 10th	Night	3 8% 2 5% 4 6% 6% 5% 8% 10% 42%	5496
	11th to 20th	Night	5% 7% 2 6% 5% 4 4 3 6% 8% 48%	5210
	21st to end	Night	8% 8% 4 8% 6% 6% 6% 5% 8% 10% 33%	5260
April	1st to 10th	Night	5% 6% 2 6% 6% 4 5% 6% 8% 10% 42%	2100
	11th to 20th	Night	3 6% 2 6% 4 5% 5% 3 6% 8% 52%	2079
	21st to end	Night	5% 4 2 5% 4 4 4 5% 7% 9% 51%	1833
May	1st to 10th	Night	4 3 1 3 3 3 4 3 6% 8% 61%	4724
	11th to 20th	Night	3 4 2 5% 4 4 5% 4 6% 8% 55%	4700
	21st to end	Night	5% 3 1 4 3 4 5% 5% 9% 11% 50%	5178
June	1st to 10th	Night	5% 5% 2 5% 3 4 4 5% 6% 8% 52%	1680
	11th to 20th	Night	3 4 2 5% 3 3 5% 4 7% 7% 57%	1680
	21st to end	Night	1 2 1 5% 3 4 3 4 6% 8% 63%	1680
July	1st to 10th	Night	1 1 1 2 1 1 2 2 3 5% 82%	3720
	11th to 20th	Night	1 1 1 1 2 1 3 4 86%	3680
	21st to end	Night	1 1 1 2 2 2 2 2 4 5% 79%	3969
August	1st to 10th	Night	1 2 1 3 2 2 2 2 4 6% 74%	2609
	11th to 20th	Night	2 1 1 3 2 2 3 3 4 7% 72%	2801
	21st to end	Night	4 2 1 4 3 3 3 3 4 6% 67%	3570
September	1st to 10th	Night	3 2 1 2 2 3 3 3 5% 7% 69%	2000
	11th to 20th	Night	3 4 2 4 3 3 3 4 5% 7% 62%	2000
	21st to end	Night	4 3 1 4 3 3 4 3 6% 8% 60%	2245
October	1st to 10th	Night	3 4 2 4 3 3 5% 4 6% 8% 57%	3920
	11th to 20th	Night	5% 5% 2 6% 3 4 6% 5% 7% 9% 50%	3897
	21st to end	Night	7% 6% 3 8% 4 5% 5% 4 5% 7% 46%	4582
November	1st to 10th	Night	10% 9% 3 7% 5% 4 5% 5% 7% 9% 35%	2727
	11th to 20th	Night	7% 11% 3 8% 7% 5% 5% 5% 6% 7% 37%	2940
	21st to end	Night	6% 14% 4 11% 5% 5% 4 5% 5% 8% 33%	2940
December	1st to 10th	Night	5% 9% 2 9% 5% 5% 4 4 8% 7% 42%	4700
	11th to 20th	Night	9% 15% 6% 15% 7% 6% 5% 5% 6% 7% 19%	5320
	21st to end	Night	11% 19% 6% 11% 5% 5% 4 4 5% 6% 24%	7106

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	58% 10% 11% 15% 6%	4723
	11th to 20th	Day	38% 8% 13% 30% 9% 2	4740
	21st to end	Day	49% 8% 12% 21% 8%	5187
February	1st to 10th	Day	48% 13% 17% 17% 4 2	1848
	11th to 20th	Day	44% 12% 17% 18% 8% 1	1854
	21st to end	Day	46% 12% 16% 18% 6% 1	1710
March	1st to 10th	Day	38% 9% 14% 20% 18% 1	4618
	11th to 20th	Day	39% 7% 10% 34% 10% 1	5006
	21st to end	Day	48% 11% 17% 18% 6%	5956
April	1st to 10th	Day	44% 10% 19% 20% 8%	2520
	11th to 20th	Day	37% 9% 16% 23% 13% 2	2492
	21st to end	Day	33% 10% 15% 27% 14% 2	2782
May	1st to 10th	Day	26% 5% 9% 33% 23% 4	8195
	11th to 20th	Day	27% 5% 17% 32% 18% 1	8163
	21st to end	Day	34% 8% 16% 34% 9%	8994
June	1st to 10th	Day	34% 8% 13% 25% 16% 4	2940
	11th to 20th	Day	27% 8% 15% 29% 19% 3	2940
	21st to end	Day	24% 5% 15% 30% 21% 4	2940
July	1st to 10th	Day	10% 3 9% 23% 29% 27%	6391
	11th to 20th	Day	12% 2 4 19% 32% 30%	6316
	21st to end	Day	15% 2 6% 30% 33% 15%	6681
August	1st to 10th	Day	14% 3 7% 24% 34% 18%	4524
	11th to 20th	Day	18% 5% 13% 37% 23% 4	4293
	21st to end	Day	26% 4 11% 26% 28% 5%	4347
September	1st to 10th	Day	16% 4 11% 29% 30% 8%	2400
	11th to 20th	Day	26% 8% 14% 25% 22% 6%	2400
	21st to end	Day	27% 6% 17% 28% 17% 5%	2151
October	1st to 10th	Day	25% 5% 13% 40% 17% 1	3280
	11th to 20th	Day	36% 8% 14% 23% 18%	3261
	21st to end	Day	40% 8% 11% 24% 14% 4	3217
November	1st to 10th	Day	46% 10% 16% 18% 8% 1	1791
	11th to 20th	Day	51% 11% 17% 13% 6% 1	1680
	21st to end	Day	49% 13% 17% 14% 7% 1	1680
December	1st to 10th	Day	41% 9% 19% 23% 8%	2700
	11th to 20th	Day	62% 10% 13% 10% 4	3108
	21st to end	Day	61% 9% 11% 14% 4	4092
January	1st to 10th	Night	59% 9% 14% 13% 5%	8172
	11th to 20th	Night	38% 7% 15% 30% 11%	8220
	21st to end	Night	51% 8% 12% 21% 8%	8994
February	1st to 10th	Night	48% 12% 18% 16% 5% 1	2770
	11th to 20th	Night	43% 9% 18% 19% 9% 1	2664
	21st to end	Night	43% 13% 16% 19% 9% 1	2095
March	1st to 10th	Night	33% 9% 15% 26% 15% 2	5496
	11th to 20th	Night	33% 7% 17% 31% 12%	5211
	21st to end	Night	43% 12% 18% 21% 6%	5260
April	1st to 10th	Night	35% 10% 22% 25% 8% 1	2100
	11th to 20th	Night	31% 8% 20% 22% 17% 1	2079
	21st to end	Night	29% 9% 17% 32% 14% 1	1833
May	1st to 10th	Night	23% 4 10% 36% 25% 2	4721
	11th to 20th	Night	26% 6% 17% 34% 17% 1	4700
	21st to end	Night	25% 9% 22% 36% 8%	5182
June	1st to 10th	Night	29% 8% 15% 28% 18% 2	1680
	11th to 20th	Night	25% 6% 18% 31% 18% 2	1680
	21st to end	Night	20% 7% 16% 34% 19% 4	1680
July	1st to 10th	Night	9% 3 10% 28% 25% 25%	3680
	11th to 20th	Night	6% 2 7% 27% 31% 27%	3632
	21st to end	Night	11% 2 8% 33% 32% 14%	3857
August	1st to 10th	Night	13% 3 7% 26% 33% 17%	2601
	11th to 20th	Night	15% 4 21% 36% 18% 5%	2825
	21st to end	Night	21% 4 14% 29% 27% 6%	3570
September	1st to 10th	Night	15% 5% 15% 28% 29% 8%	2000
	11th to 20th	Night	22% 7% 13% 29% 23% 7%	2000
	21st to end	Night	21% 6% 17% 34% 16% 5%	2245
October	1st to 10th	Night	26% 5% 12% 43% 14% 1	3920
	11th to 20th	Night	32% 6% 16% 29% 16% 1	3897
	21st to end	Night	39% 7% 12% 28% 12% 3	4582
November	1st to 10th	Night	46% 9% 17% 19% 8% 1	2727
	11th to 20th	Night	47% 11% 17% 18% 6% 1	2940
	21st to end	Night	49% 10% 16% 17% 7% 1	2940
December	1st to 10th	Night	39% 8% 18% 27% 7%	4700
	11th to 20th	Night	63% 11% 13% 9% 4	5316
	21st to end	Night	60% 8% 13% 13% 5%	7106

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	17% 13% 28% 30% 10% 3	220
	11th to 20th	Day	16% 9% 30% 28% 14% 3	220
	21st to end	Day	15% 7% 30% 36% 10% 3	242
February	1st to 10th	Day	12% 19% 38% 26% 4 1	388
	11th to 20th	Day	13% 19% 37% 24% 7% 1	425
	21st to end	Day	12% 22% 36% 23% 6% 1	436
March	1st to 10th	Day	13% 24% 35% 21% 6% 1	540
	11th to 20th	Day	18% 20% 30% 21% 11%	540
	21st to end	Day	19% 24% 33% 21% 4	594
April	1st to 10th	Day	18% 22% 30% 21% 7% 1	540
	11th to 20th	Day	14% 29% 31% 17% 7% 2	532
	21st to end	Day	12% 23% 34% 21% 9% 2	540
May	1st to 10th	Day	12% 15% 39% 25% 7% 1	543
	11th to 20th	Day	20% 15% 28% 24% 10% 2	568
	21st to end	Day	12% 16% 30% 26% 13% 3	617
June	1st to 10th	Day	13% 19% 31% 25% 10% 2	570
	11th to 20th	Day	13% 21% 36% 22% 7% 1	570
	21st to end	Day	7% 16% 31% 30% 14% 2	570
July	1st to 10th	Day	5% 13% 33% 37% 11% 1	566
	11th to 20th	Day	4 15% 32% 34% 12% 3	545
	21st to end	Day	4 9% 30% 38% 16% 3	575
August	1st to 10th	Day	5% 9% 28% 37% 18% 3	527
	11th to 20th	Day	3 9% 25% 40% 18% 6%	517
	21st to end	Day	7% 12% 30% 31% 15% 4	583
September	1st to 10th	Day	5% 11% 32% 31% 16% 5%	530
	11th to 20th	Day	8% 12% 33% 33% 12% 2	530
	21st to end	Day	12% 17% 30% 28% 12% 2	530
October	1st to 10th	Day	13% 13% 31% 26% 15% 2	530
	11th to 20th	Day	14% 15% 30% 26% 12% 3	530
	21st to end	Day	14% 18% 31% 25% 9% 2	380
November	1st to 10th	Day	18% 15% 30% 27% 9% 1	297
	11th to 20th	Day	19% 17% 27% 20% 13% 4	220
	21st to end	Day	11% 9% 30% 33% 12% 5%	220
December	1st to 10th	Day	13% 14% 25% 25% 16% 7%	220
	11th to 20th	Day	12% 11% 31% 35% 10%	220
	21st to end	Day	10% 10% 34% 33% 12% 2	242
January	1st to 10th	Night	18% 12% 31% 25% 13% 1	840
	11th to 20th	Night	15% 9% 31% 31% 13% 1	840
	21st to end	Night	15% 7% 29% 33% 14% 2	924
February	1st to 10th	Night	13% 9% 34% 32% 11% 1	840
	11th to 20th	Night	11% 12% 30% 34% 12% 1	824
	21st to end	Night	11% 15% 32% 28% 14% 1	692
March	1st to 10th	Night	14% 9% 32% 34% 10% 1	840
	11th to 20th	Night	9% 12% 34% 30% 14% 1	840
	21st to end	Night	11% 14% 36% 31% 7% 1	924
April	1st to 10th	Night	9% 12% 33% 32% 13% 1	840
	11th to 20th	Night	7% 15% 35% 31% 10% 2	831
	21st to end	Night	8% 13% 40% 29% 10% 1	573
May	1st to 10th	Night	6% 12% 35% 34% 12% 1	420
	11th to 20th	Night	10% 9% 25% 37% 17% 1	414
	21st to end	Night	8% 7% 30% 36% 18% 1	455
June	1st to 10th	Night	10% 7% 34% 34% 14% 1	420
	11th to 20th	Night	9% 14% 36% 32% 10%	420
	21st to end	Night	3 11% 35% 33% 18%	420
July	1st to 10th	Night	5% 6% 33% 42% 15%	410
	11th to 20th	Night	9% 39% 38% 13% 1	398
	21st to end	Night	1 5% 30% 42% 21%	438
August	1st to 10th	Night	2 6% 25% 41% 25% 2	398
	11th to 20th	Night	3 5% 24% 38% 27% 2	529
	21st to end	Night	5% 7% 26% 39% 21% 2	855
September	1st to 10th	Night	4 5% 28% 38% 23% 3	800
	11th to 20th	Night	6% 6% 24% 32% 27% 5%	800
	21st to end	Night	7% 7% 28% 36% 19% 4	800
October	1st to 10th	Night	9% 8% 26% 35% 21% 1	800
	11th to 20th	Night	9% 9% 29% 32% 19% 2	800
	21st to end	Night	13% 11% 32% 30% 11% 3	880
November	1st to 10th	Night	15% 9% 31% 35% 9%	820
	11th to 20th	Night	16% 11% 31% 29% 11% 2	840
	21st to end	Night	15% 8% 31% 29% 14% 2	840
December	1st to 10th	Night	13% 8% 32% 31% 14% 2	840
	11th to 20th	Night	16% 8% 33% 34% 9%	840
	21st to end	Night	16% 9% 34% 34% 6% 1	924

Page generated at 2026-07-13 00:14:49. Version ac07

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