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 2024-02-10.

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% 7% 3 6% 5% 3 5% 5% 6% 8% 46%	78140
	Night	6% 9% 4 7% 5% 3 5% 5% 6% 8% 43%	80788
Transparency	Day	36% 9% 14% 22% 15% 4	77867
	Night	40% 9% 15% 22% 12% 2	80641
Seeing	Day	10% 16% 31% 28% 12% 2	13301
	Night	10% 9% 30% 34% 16% 2	22450

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	8% 16% 6% 10% 7% 4 7% 6% 6% 7% 24%	2539
	11th to 20th	Day	8% 16% 7% 9% 6% 3 5% 4 4 6% 31%	2516
	21st to end	Day	15% 17% 5% 9% 8% 4 6% 5% 6% 5% 20%	2794
February	1st to 10th	Day	7% 10% 3 8% 7% 5% 6% 6% 7% 8% 34%	1664
	11th to 20th	Day	5% 9% 3 7% 6% 3 5% 5% 7% 9% 39%	1575
	21st to end	Day	5% 9% 4 8% 7% 4 6% 8% 8% 7% 34%	1462
March	1st to 10th	Day	6% 11% 4 7% 5% 4 6% 6% 6% 9% 36%	1800
	11th to 20th	Day	6% 10% 3 6% 7% 5% 7% 6% 6% 9% 34%	1931
	21st to end	Day	7% 9% 3 6% 6% 4 7% 7% 8% 10% 33%	2312
April	1st to 10th	Day	7% 8% 4 7% 7% 4 7% 7% 9% 8% 33%	2160
	11th to 20th	Day	6% 7% 3 5% 7% 3 6% 5% 6% 10% 41%	2132
	21st to end	Day	5% 5% 3 5% 5% 3 6% 6% 8% 9% 45%	2384
May	1st to 10th	Day	5% 4 1 5% 5% 3 5% 6% 5% 10% 51%	2520
	11th to 20th	Day	8% 5% 2 5% 6% 4 6% 6% 7% 9% 42%	2477
	21st to end	Day	10% 6% 2 5% 7% 4 6% 6% 5% 8% 42%	2723
June	1st to 10th	Day	8% 5% 2 5% 5% 4 6% 6% 7% 9% 44%	2520
	11th to 20th	Day	5% 4 2 5% 5% 3 5% 6% 6% 9% 51%	2520
	21st to end	Day	4 3 2 4 4 3 4 4 5% 7% 60%	2520
July	1st to 10th	Day	2 2 1 3 3 2 4 5% 5% 7% 67%	2520
	11th to 20th	Day	2 2 1 3 4 2 3 3 5% 6% 70%	2520
	21st to end	Day	1 1 1 2 2 2 2 2 3 4 80%	2741
August	1st to 10th	Day	2 2 1 2 3 2 3 3 4 6% 72%	2507
	11th to 20th	Day	1 2 1 2 2 2 3 3 4 6% 73%	2354
	21st to end	Day	2 2 1 2 3 3 4 5% 5% 7% 65%	2398
September	1st to 10th	Day	3 2 1 3 2 2 3 3 5% 7% 70%	2160
	11th to 20th	Day	4 4 2 4 4 3 6% 5% 6% 8% 54%	2160
	21st to end	Day	6% 4 2 4 5% 4 5% 5% 5% 7% 56%	1937
October	1st to 10th	Day	6% 4 2 5% 6% 4 4 5% 5% 8% 53%	1800
	11th to 20th	Day	6% 6% 2 4 6% 3 5% 5% 7% 10% 47%	1800
	21st to end	Day	9% 7% 3 5% 5% 3 5% 6% 6% 9% 41%	1798
November	1st to 10th	Day	7% 10% 4 7% 6% 4 5% 6% 7% 9% 36%	1617
	11th to 20th	Day	5% 10% 4 9% 8% 5% 7% 7% 6% 7% 33%	1520
	21st to end	Day	5% 12% 5% 9% 7% 3 6% 7% 7% 8% 32%	1520
December	1st to 10th	Day	7% 11% 5% 9% 7% 5% 5% 6% 7% 6% 32%	1520
	11th to 20th	Day	7% 14% 5% 13% 9% 5% 5% 6% 5% 7% 23%	1925
	21st to end	Day	8% 17% 7% 13% 7% 4 5% 4 4 5% 24%	2794
January	1st to 10th	Night	7% 19% 6% 12% 8% 5% 5% 5% 5% 5% 24%	4406
	11th to 20th	Night	10% 16% 7% 8% 6% 3 5% 4 5% 7% 29%	4382
	21st to end	Night	11% 20% 6% 14% 9% 4 5% 5% 4 6% 17%	4862
February	1st to 10th	Night	7% 12% 4 8% 7% 4 5% 6% 7% 8% 33%	2499
	11th to 20th	Night	6% 8% 3 6% 6% 4 5% 7% 6% 8% 42%	2272
	21st to end	Night	5% 9% 4 9% 6% 4 6% 7% 7% 9% 36%	1793
March	1st to 10th	Night	7% 11% 3 6% 5% 3 6% 6% 6% 9% 37%	2160
	11th to 20th	Night	4 7% 3 5% 6% 4 6% 6% 8% 11% 41%	2025
	21st to end	Night	6% 8% 4 5% 5% 5% 6% 6% 7% 10% 39%	2043
April	1st to 10th	Night	5% 6% 3 6% 7% 3 5% 6% 9% 11% 40%	1800
	11th to 20th	Night	4 6% 3 5% 5% 4 5% 4 6% 8% 51%	1779
	21st to end	Night	6% 4 1 4 5% 3 4 6% 7% 9% 50%	1572
May	1st to 10th	Night	4 3 2 4 4 3 5% 4 8% 10% 54%	1440
	11th to 20th	Night	7% 3 2 4 4 3 5% 6% 6% 9% 50%	1416
	21st to end	Night	6% 3 2 5% 4 3 6% 7% 9% 11% 46%	1552
June	1st to 10th	Night	6% 5% 2 4 4 3 5% 5% 7% 8% 50%	1440
	11th to 20th	Night	4 4 2 4 3 2 5% 5% 7% 8% 55%	1440
	21st to end	Night	2 2 1 3 4 2 4 5% 6% 7% 65%	1440
July	1st to 10th	Night	2 1 1 3 2 2 3 5% 5% 7% 70%	1440
	11th to 20th	Night	1 1 1 1 2 1 3 3 4 6% 78%	1440
	21st to end	Night	1 1 1 2 2 3 4 86%	1576
August	1st to 10th	Night	1 1 1 2 2 1 3 3 4 7% 76%	1432
	11th to 20th	Night	2 1 1 2 2 1 2 3 4 6% 77%	1543
	21st to end	Night	2 1 1 2 3 2 3 4 5% 7% 70%	1957
September	1st to 10th	Night	3 2 1 2 2 2 3 3 5% 8% 70%	1800
	11th to 20th	Night	3 3 2 3 3 2 4 5% 5% 8% 62%	1800
	21st to end	Night	4 3 1 3 4 2 4 4 6% 9% 60%	2019
October	1st to 10th	Night	6% 5% 2 5% 5% 3 5% 5% 6% 7% 53%	2160
	11th to 20th	Night	5% 4 2 4 4 3 6% 6% 7% 9% 50%	2160
	21st to end	Night	10% 7% 2 5% 5% 4 5% 5% 5% 8% 45%	2557
November	1st to 10th	Night	10% 8% 3 7% 5% 3 5% 6% 7% 9% 36%	2461
	11th to 20th	Night	6% 10% 3 7% 7% 4 5% 6% 6% 7% 38%	2660
	21st to end	Night	5% 13% 6% 9% 6% 3 5% 5% 5% 8% 34%	2660
December	1st to 10th	Night	8% 13% 5% 10% 7% 4 5% 5% 5% 7% 31%	2660
	11th to 20th	Night	9% 14% 5% 12% 9% 4 5% 6% 6% 7% 23%	3280
	21st to end	Night	10% 18% 7% 11% 7% 4 5% 4 5% 5% 24%	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	57% 15% 11% 12% 5%	2539
	11th to 20th	Day	55% 10% 14% 17% 3	2540
	21st to end	Day	62% 13% 13% 9% 3	2794
February	1st to 10th	Day	47% 13% 18% 17% 4 1	1664
	11th to 20th	Day	42% 13% 18% 19% 8% 1	1584
	21st to end	Day	47% 13% 17% 17% 6% 1	1462
March	1st to 10th	Day	44% 12% 15% 20% 9% 1	1800
	11th to 20th	Day	46% 11% 13% 23% 7%	1931
	21st to end	Day	45% 13% 18% 18% 6% 1	2312
April	1st to 10th	Day	44% 10% 18% 19% 8% 1	2160
	11th to 20th	Day	39% 10% 16% 21% 11% 2	2132
	21st to end	Day	34% 11% 16% 25% 13% 2	2384
May	1st to 10th	Day	28% 11% 18% 29% 12% 3	2520
	11th to 20th	Day	37% 10% 16% 26% 12%	2480
	21st to end	Day	41% 9% 15% 26% 9%	2724
June	1st to 10th	Day	36% 9% 15% 25% 13% 4	2520
	11th to 20th	Day	28% 9% 17% 29% 15% 2	2520
	21st to end	Day	23% 5% 15% 29% 23% 4	2520
July	1st to 10th	Day	17% 6% 13% 25% 28% 11%	2451
	11th to 20th	Day	17% 4 8% 21% 34% 16%	2445
	21st to end	Day	10% 3 7% 23% 38% 21%	2589
August	1st to 10th	Day	14% 5% 10% 26% 32% 13%	2490
	11th to 20th	Day	13% 4 11% 29% 36% 8%	2354
	21st to end	Day	18% 6% 11% 30% 29% 6%	2398
September	1st to 10th	Day	16% 5% 12% 30% 29% 9%	2160
	11th to 20th	Day	27% 8% 14% 23% 22% 7%	2160
	21st to end	Day	28% 7% 17% 27% 17% 5%	1937
October	1st to 10th	Day	30% 7% 15% 32% 14% 2	1800
	11th to 20th	Day	32% 10% 17% 27% 13%	1800
	21st to end	Day	40% 9% 14% 24% 13%	1798
November	1st to 10th	Day	46% 11% 15% 18% 9% 1	1617
	11th to 20th	Day	49% 12% 18% 14% 5% 1	1520
	21st to end	Day	48% 13% 17% 14% 7% 1	1520
December	1st to 10th	Day	50% 12% 15% 16% 7%	1520
	11th to 20th	Day	58% 14% 16% 9% 3	1928
	21st to end	Day	62% 9% 11% 12% 5%	2794
January	1st to 10th	Night	58% 11% 15% 10% 5%	4406
	11th to 20th	Night	55% 8% 14% 18% 6%	4420
	21st to end	Night	67% 11% 11% 9% 2	4862
February	1st to 10th	Night	49% 12% 19% 16% 4 1	2499
	11th to 20th	Night	42% 10% 19% 19% 8% 1	2274
	21st to end	Night	43% 13% 15% 19% 9%	1793
March	1st to 10th	Night	43% 10% 17% 21% 8% 1	2160
	11th to 20th	Night	37% 11% 18% 26% 9%	2026
	21st to end	Night	41% 12% 19% 22% 6%	2043
April	1st to 10th	Night	36% 10% 20% 24% 9% 1	1800
	11th to 20th	Night	32% 8% 19% 22% 17% 1	1779
	21st to end	Night	30% 9% 17% 30% 13% 1	1572
May	1st to 10th	Night	25% 8% 18% 33% 14% 2	1440
	11th to 20th	Night	30% 8% 20% 30% 11% 1	1416
	21st to end	Night	29% 11% 18% 31% 10% 1	1552
June	1st to 10th	Night	31% 8% 16% 28% 16% 2	1440
	11th to 20th	Night	26% 7% 21% 31% 14% 1	1440
	21st to end	Night	18% 7% 16% 35% 19% 4	1440
July	1st to 10th	Night	15% 6% 16% 30% 24% 10%	1400
	11th to 20th	Night	10% 4 12% 30% 29% 16%	1392
	21st to end	Night	4 3 7% 27% 41% 18%	1488
August	1st to 10th	Night	11% 4 11% 30% 30% 14%	1424
	11th to 20th	Night	10% 4 14% 33% 30% 9%	1543
	21st to end	Night	14% 6% 12% 32% 29% 6%	1957
September	1st to 10th	Night	15% 5% 15% 28% 29% 8%	1800
	11th to 20th	Night	22% 8% 13% 26% 24% 8%	1800
	21st to end	Night	21% 6% 17% 34% 16% 6%	2019
October	1st to 10th	Night	31% 6% 13% 31% 18% 1	2160
	11th to 20th	Night	30% 9% 17% 29% 14% 1	2160
	21st to end	Night	37% 9% 13% 29% 11% 1	2557
November	1st to 10th	Night	45% 10% 17% 20% 8% 1	2461
	11th to 20th	Night	45% 12% 18% 18% 5% 2	2660
	21st to end	Night	49% 10% 16% 17% 8% 1	2660
December	1st to 10th	Night	54% 9% 15% 17% 4	2660
	11th to 20th	Night	59% 15% 15% 8% 3	3276
	21st to end	Night	61% 9% 13% 12% 5%	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	18% 13% 27% 27% 12% 3	180
	11th to 20th	Day	18% 10% 29% 26% 13% 4	180
	21st to end	Day	16% 8% 34% 30% 9% 4	198
February	1st to 10th	Day	12% 21% 37% 25% 4 1	330
	11th to 20th	Day	13% 23% 36% 21% 6% 1	335
	21st to end	Day	8% 20% 38% 25% 7% 1	338
March	1st to 10th	Day	12% 24% 36% 20% 7% 1	420
	11th to 20th	Day	15% 20% 32% 22% 12%	420
	21st to end	Day	18% 23% 34% 21% 4	462
April	1st to 10th	Day	18% 22% 30% 21% 7% 2	420
	11th to 20th	Day	12% 30% 30% 19% 7% 3	412
	21st to end	Day	10% 24% 35% 22% 8% 2	420
May	1st to 10th	Day	11% 15% 39% 28% 7% 1	423
	11th to 20th	Day	18% 12% 28% 27% 11% 3	448
	21st to end	Day	11% 15% 29% 28% 14% 4	485
June	1st to 10th	Day	9% 20% 32% 25% 12% 2	450
	11th to 20th	Day	10% 23% 36% 22% 8% 1	450
	21st to end	Day	5% 16% 29% 32% 15% 3	450
July	1st to 10th	Day	5% 10% 30% 41% 13% 1	446
	11th to 20th	Day	5% 14% 31% 36% 12% 4	444
	21st to end	Day	3 9% 30% 39% 17% 3	487
August	1st to 10th	Day	5% 10% 26% 36% 19% 3	447
	11th to 20th	Day	2 8% 24% 41% 19% 6%	437
	21st to end	Day	6% 13% 31% 31% 15% 5%	495
September	1st to 10th	Day	6% 12% 36% 30% 14% 3	450
	11th to 20th	Day	7% 12% 31% 33% 14% 2	450
	21st to end	Day	11% 16% 29% 29% 13% 2	450
October	1st to 10th	Day	13% 12% 30% 26% 16% 2	450
	11th to 20th	Day	12% 14% 31% 26% 13% 3	450
	21st to end	Day	14% 18% 29% 26% 10% 3	313
November	1st to 10th	Day	14% 16% 32% 29% 9% 1	243
	11th to 20th	Day	16% 19% 28% 17% 14% 5%	180
	21st to end	Day	11% 9% 29% 32% 14% 5%	180
December	1st to 10th	Day	12% 14% 25% 26% 16% 7%	180
	11th to 20th	Day	8% 9% 34% 37% 11% 1	180
	21st to end	Day	8% 10% 34% 33% 13% 3	198
January	1st to 10th	Night	18% 12% 30% 25% 14% 1	760
	11th to 20th	Night	16% 8% 28% 32% 14% 1	760
	21st to end	Night	15% 7% 27% 33% 15% 2	836
February	1st to 10th	Night	15% 9% 33% 31% 11% 1	758
	11th to 20th	Night	12% 11% 30% 34% 13% 1	704
	21st to end	Night	10% 13% 30% 30% 15% 2	592
March	1st to 10th	Night	14% 8% 32% 34% 11% 1	720
	11th to 20th	Night	7% 11% 33% 32% 15% 1	720
	21st to end	Night	10% 12% 36% 33% 8% 1	792
April	1st to 10th	Night	9% 12% 32% 33% 14% 1	720
	11th to 20th	Night	7% 14% 34% 32% 11% 2	711
	21st to end	Night	6% 12% 40% 30% 11% 1	492
May	1st to 10th	Night	5% 10% 34% 35% 14% 2	360
	11th to 20th	Night	9% 6% 22% 41% 20% 1	354
	21st to end	Night	7% 5% 27% 39% 21% 1	389
June	1st to 10th	Night	8% 6% 33% 36% 16% 1	360
	11th to 20th	Night	7% 10% 37% 35% 11%	360
	21st to end	Night	2 9% 33% 36% 20%	360
July	1st to 10th	Night	3 3 30% 46% 17%	350
	11th to 20th	Night	6% 36% 42% 15% 1	348
	21st to end	Night	1 5% 27% 45% 23% 1	394
August	1st to 10th	Night	1 5% 22% 42% 28% 2	358
	11th to 20th	Night	2 3 21% 41% 30% 3	475
	21st to end	Night	4 7% 26% 39% 22% 2	769
September	1st to 10th	Night	4 5% 28% 37% 23% 3	720
	11th to 20th	Night	5% 5% 22% 33% 29% 6%	720
	21st to end	Night	5% 6% 27% 37% 21% 4	720
October	1st to 10th	Night	8% 7% 24% 36% 22% 2	720
	11th to 20th	Night	8% 7% 28% 33% 22% 3	720
	21st to end	Night	13% 10% 31% 31% 13% 3	792
November	1st to 10th	Night	14% 8% 31% 37% 10%	740
	11th to 20th	Night	15% 11% 31% 29% 12% 2	760
	21st to end	Night	14% 8% 30% 29% 16% 2	760
December	1st to 10th	Night	13% 8% 32% 32% 14% 2	760
	11th to 20th	Night	15% 6% 33% 36% 10%	760
	21st to end	Night	16% 9% 32% 35% 7% 1	836

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