Ridgway Nature & Science Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ridgway Nature & Science Center clear sky chart from 2005-11-06 to 2024-03-06.

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	4 7% 3 6% 6% 3 5% 5% 6% 7% 48%	78701
	Night	2 6% 3 6% 5% 3 4 5% 5% 7% 54%	80880
Transparency	Day	38% 8% 9% 19% 19% 7%	78421
	Night	31% 7% 11% 22% 21% 8%	80681
Seeing	Day	11% 22% 31% 24% 10% 2	14303
	Night	7% 12% 28% 32% 18% 3	24616

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	1 8% 4 12% 10% 3 3 4 6% 6% 42%	2771
	11th to 20th	Day	2 10% 5% 9% 8% 4 5% 4 6% 7% 40%	2860
	21st to end	Day	1 10% 5% 10% 5% 3 4 4 4 5% 47%	3146
February	1st to 10th	Day	2 12% 6% 9% 6% 2 5% 4 6% 6% 41%	1710
	11th to 20th	Day	2 9% 5% 8% 6% 3 5% 5% 5% 8% 44%	1703
	21st to end	Day	1 10% 6% 10% 7% 4 5% 5% 5% 5% 43%	1570
March	1st to 10th	Day	3 10% 4 9% 5% 2 4 5% 6% 8% 44%	2033
	11th to 20th	Day	2 9% 4 7% 5% 3 4 6% 6% 7% 47%	1980
	21st to end	Day	1 11% 5% 7% 7% 3 6% 6% 6% 8% 39%	2182
April	1st to 10th	Day	3 9% 3 7% 5% 3 4 6% 6% 8% 47%	2160
	11th to 20th	Day	2 11% 4 7% 5% 3 5% 7% 6% 8% 42%	2131
	21st to end	Day	4 11% 3 5% 6% 3 5% 4 5% 8% 46%	2160
May	1st to 10th	Day	6% 7% 3 6% 6% 3 6% 5% 7% 8% 43%	2293
	11th to 20th	Day	4 7% 3 6% 6% 3 6% 7% 6% 9% 44%	2320
	21st to end	Day	4 5% 2 5% 6% 4 5% 4 6% 8% 51%	2724
June	1st to 10th	Day	2 3 2 4 4 4 6% 4 5% 8% 58%	2520
	11th to 20th	Day	3 2 1 4 4 3 4 4 6% 7% 62%	2520
	21st to end	Day	3 3 2 3 5% 4 5% 5% 5% 8% 58%	2520
July	1st to 10th	Day	6% 4 2 5% 6% 3 7% 7% 7% 8% 46%	2505
	11th to 20th	Day	5% 4 2 5% 7% 4 8% 9% 9% 9% 38%	2340
	21st to end	Day	9% 6% 4 7% 7% 5% 9% 7% 8% 9% 29%	2545
August	1st to 10th	Day	9% 6% 3 6% 8% 4 7% 6% 7% 8% 35%	2328
	11th to 20th	Day	6% 5% 3 6% 7% 4 7% 7% 7% 7% 42%	2232
	21st to end	Day	5% 5% 2 7% 9% 5% 7% 5% 7% 9% 41%	2376
September	1st to 10th	Day	7% 5% 2 6% 7% 4 5% 4 5% 8% 48%	2160
	11th to 20th	Day	6% 4 2 4 6% 3 5% 5% 6% 7% 52%	2149
	21st to end	Day	5% 3 2 5% 5% 3 3 4 4 6% 61%	1900
October	1st to 10th	Day	6% 5% 2 4 4 3 4 4 5% 6% 57%	1800
	11th to 20th	Day	4 4 2 3 3 2 3 3 4 6% 67%	1800
	21st to end	Day	3 8% 2 4 4 2 3 4 3 5% 61%	1980
November	1st to 10th	Day	2 4 2 4 3 2 3 2 5% 6% 68%	1836
	11th to 20th	Day	2 7% 3 4 3 2 3 4 5% 5% 63%	1687
	21st to end	Day	2 5% 4 7% 4 3 4 4 3 6% 59%	1520
December	1st to 10th	Day	2 8% 5% 8% 6% 2 4 4 5% 6% 50%	1520
	11th to 20th	Day	3 9% 4 10% 5% 3 5% 4 5% 7% 44%	1926
	21st to end	Day	1 7% 3 9% 8% 4 4 5% 5% 6% 48%	2794
January	1st to 10th	Night	1 8% 5% 15% 8% 3 5% 4 4 5% 41%	4211
	11th to 20th	Night	1 12% 5% 7% 7% 5% 5% 6% 5% 7% 40%	4110
	21st to end	Night	1 10% 6% 10% 6% 3 4 4 5% 6% 47%	4521
February	1st to 10th	Night	2 9% 6% 9% 5% 3 4 3 4 6% 49%	2470
	11th to 20th	Night	2 7% 4 7% 6% 3 6% 5% 5% 7% 48%	2364
	21st to end	Night	1 10% 4 8% 7% 3 4 4 5% 6% 47%	1884
March	1st to 10th	Night	1 8% 3 6% 5% 3 5% 5% 5% 8% 52%	2040
	11th to 20th	Night	1 7% 4 6% 5% 3 4 5% 5% 6% 54%	1980
	21st to end	Night	2 11% 3 6% 4 3 4 5% 6% 7% 48%	2174
April	1st to 10th	Night	4 8% 3 6% 5% 2 5% 5% 7% 7% 48%	1800
	11th to 20th	Night	3 11% 4 5% 4 3 4 5% 7% 8% 46%	1777
	21st to end	Night	4 9% 3 4 4 3 4 5% 5% 7% 51%	1800
May	1st to 10th	Night	3 5% 2 5% 4 3 5% 5% 7% 7% 55%	1664
	11th to 20th	Night	3 5% 2 4 4 3 4 3 6% 9% 57%	1573
	21st to end	Night	3 3 1 3 3 3 4 4 6% 8% 62%	1552
June	1st to 10th	Night	2 2 1 2 4 2 3 4 5% 8% 69%	1440
	11th to 20th	Night	2 1 1 2 2 2 4 3 5% 6% 72%	1440
	21st to end	Night	1 1 1 2 3 2 4 5% 7% 8% 66%	1440
July	1st to 10th	Night	2 2 1 3 3 4 5% 7% 8% 9% 57%	1449
	11th to 20th	Night	2 2 1 3 5% 3 6% 6% 8% 11% 52%	1620
	21st to end	Night	3 2 2 4 6% 4 7% 8% 10% 13% 39%	1773
August	1st to 10th	Night	3 2 1 3 4 3 5% 6% 7% 10% 54%	1611
	11th to 20th	Night	3 3 1 4 5% 2 5% 6% 6% 8% 56%	1667
	21st to end	Night	3 3 1 4 4 2 5% 5% 6% 10% 56%	1980
September	1st to 10th	Night	3 3 1 3 4 2 4 5% 6% 11% 57%	1800
	11th to 20th	Night	3 2 1 3 3 3 4 6% 5% 7% 62%	1807
	21st to end	Night	3 3 1 3 2 1 3 3 3 5% 71%	2060
October	1st to 10th	Night	4 4 1 3 3 2 4 4 4 8% 63%	2160
	11th to 20th	Night	2 3 1 2 3 1 3 4 3 5% 72%	2160
	21st to end	Night	4 7% 3 4 3 1 3 3 3 5% 65%	2376
November	1st to 10th	Night	2 5% 1 2 2 2 3 4 5% 8% 66%	2221
	11th to 20th	Night	3 8% 2 3 3 2 3 3 4 5% 64%	2492
	21st to end	Night	2 7% 5% 6% 4 2 3 3 4 7% 57%	2660
December	1st to 10th	Night	2 8% 3 5% 5% 3 4 4 4 6% 55%	2660
	11th to 20th	Night	2 7% 4 7% 6% 4 5% 6% 6% 8% 46%	3271
	21st to end	Night	1 7% 5% 9% 7% 3 4 4 4 5% 49%	4873

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	43% 7% 13% 16% 17% 4	2772
	11th to 20th	Day	45% 7% 13% 21% 11% 2	2860
	21st to end	Day	42% 6% 7% 24% 16% 4	3146
February	1st to 10th	Day	46% 6% 12% 15% 14% 6%	1710
	11th to 20th	Day	42% 6% 7% 19% 19% 7%	1712
	21st to end	Day	45% 5% 6% 18% 19% 7%	1570
March	1st to 10th	Day	42% 7% 8% 19% 20% 4	2033
	11th to 20th	Day	37% 8% 12% 25% 14% 4	1980
	21st to end	Day	47% 8% 8% 20% 13% 3	2182
April	1st to 10th	Day	39% 8% 8% 21% 17% 6%	2160
	11th to 20th	Day	43% 9% 8% 19% 18% 4	2134
	21st to end	Day	39% 9% 10% 26% 15% 2	2160
May	1st to 10th	Day	42% 8% 7% 22% 19% 2	2293
	11th to 20th	Day	40% 10% 10% 24% 13% 3	2323
	21st to end	Day	33% 8% 9% 22% 22% 6%	2724
June	1st to 10th	Day	25% 9% 9% 24% 23% 10%	2520
	11th to 20th	Day	24% 7% 7% 15% 28% 19%	2520
	21st to end	Day	27% 8% 7% 15% 23% 19%	2520
July	1st to 10th	Day	38% 11% 10% 10% 18% 14%	2436
	11th to 20th	Day	42% 15% 14% 11% 10% 8%	2271
	21st to end	Day	51% 14% 13% 10% 9% 2	2404
August	1st to 10th	Day	48% 12% 10% 9% 14% 7%	2313
	11th to 20th	Day	43% 11% 11% 11% 17% 7%	2232
	21st to end	Day	42% 11% 11% 15% 18% 3	2376
September	1st to 10th	Day	39% 8% 9% 11% 23% 10%	2160
	11th to 20th	Day	34% 9% 9% 14% 25% 9%	2149
	21st to end	Day	29% 7% 6% 21% 29% 8%	1900
October	1st to 10th	Day	32% 8% 7% 21% 23% 9%	1800
	11th to 20th	Day	23% 5% 5% 26% 33% 9%	1800
	21st to end	Day	28% 5% 8% 27% 26% 6%	1980
November	1st to 10th	Day	22% 5% 11% 24% 32% 7%	1836
	11th to 20th	Day	26% 3 10% 30% 25% 7%	1687
	21st to end	Day	30% 5% 9% 24% 21% 11%	1520
December	1st to 10th	Day	37% 6% 12% 24% 16% 5%	1520
	11th to 20th	Day	42% 6% 9% 19% 22% 3	1924
	21st to end	Day	35% 7% 9% 18% 21% 11%	2794
January	1st to 10th	Night	45% 5% 9% 21% 14% 6%	4211
	11th to 20th	Night	45% 7% 11% 22% 13% 3	4110
	21st to end	Night	39% 5% 8% 26% 18% 4	4521
February	1st to 10th	Night	41% 5% 11% 19% 17% 7%	2470
	11th to 20th	Night	37% 5% 9% 23% 19% 7%	2365
	21st to end	Night	39% 5% 8% 19% 22% 6%	1884
March	1st to 10th	Night	33% 7% 9% 21% 26% 4	2040
	11th to 20th	Night	32% 6% 11% 28% 19% 4	1980
	21st to end	Night	37% 7% 13% 24% 16% 3	2174
April	1st to 10th	Night	35% 8% 11% 22% 19% 5%	1800
	11th to 20th	Night	37% 9% 11% 20% 20% 3	1777
	21st to end	Night	35% 8% 11% 27% 17% 2	1800
May	1st to 10th	Night	31% 6% 11% 29% 20% 3	1664
	11th to 20th	Night	27% 9% 13% 31% 17% 2	1574
	21st to end	Night	22% 8% 13% 25% 25% 7%	1552
June	1st to 10th	Night	15% 7% 11% 27% 31% 10%	1440
	11th to 20th	Night	16% 5% 7% 19% 32% 21%	1440
	21st to end	Night	15% 8% 9% 18% 30% 20%	1440
July	1st to 10th	Night	23% 11% 13% 13% 23% 16%	1409
	11th to 20th	Night	26% 11% 20% 20% 13% 11%	1566
	21st to end	Night	33% 16% 23% 15% 9% 3	1674
August	1st to 10th	Night	25% 12% 19% 18% 18% 8%	1602
	11th to 20th	Night	24% 9% 18% 18% 21% 10%	1667
	21st to end	Night	25% 10% 15% 21% 23% 6%	1980
September	1st to 10th	Night	24% 9% 12% 17% 28% 10%	1800
	11th to 20th	Night	21% 9% 12% 21% 26% 11%	1807
	21st to end	Night	17% 6% 7% 28% 33% 9%	2060
October	1st to 10th	Night	24% 5% 11% 23% 26% 11%	2160
	11th to 20th	Night	17% 5% 8% 25% 33% 12%	2160
	21st to end	Night	25% 4 8% 30% 26% 8%	2376
November	1st to 10th	Night	20% 7% 12% 24% 27% 10%	2221
	11th to 20th	Night	25% 4 10% 26% 27% 8%	2492
	21st to end	Night	30% 5% 7% 22% 24% 12%	2660
December	1st to 10th	Night	32% 5% 14% 21% 20% 7%	2660
	11th to 20th	Night	36% 7% 10% 20% 21% 6%	3272
	21st to end	Night	38% 6% 9% 15% 21% 12%	4873

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	14% 19% 33% 21% 12% 1	270
	11th to 20th	Day	13% 27% 31% 21% 7% 1	270
	21st to end	Day	4 21% 41% 25% 7% 1	297
February	1st to 10th	Day	14% 34% 30% 18% 3 1	270
	11th to 20th	Day	15% 36% 33% 12% 4	270
	21st to end	Day	21% 34% 28% 14% 3	225
March	1st to 10th	Day	19% 36% 28% 14% 3	438
	11th to 20th	Day	14% 31% 30% 20% 5%	420
	21st to end	Day	19% 40% 28% 11% 1	462
April	1st to 10th	Day	17% 31% 33% 14% 3 1	420
	11th to 20th	Day	22% 37% 26% 11% 3	412
	21st to end	Day	17% 33% 32% 13% 4	420
May	1st to 10th	Day	15% 34% 33% 14% 4	423
	11th to 20th	Day	13% 25% 34% 21% 7% 1	467
	21st to end	Day	12% 24% 29% 21% 11% 3	679
June	1st to 10th	Day	5% 13% 34% 29% 16% 3	630
	11th to 20th	Day	7% 17% 35% 26% 11% 3	630
	21st to end	Day	3 16% 36% 26% 16% 3	630
July	1st to 10th	Day	4 7% 26% 37% 21% 4	606
	11th to 20th	Day	7% 6% 26% 37% 20% 5%	444
	21st to end	Day	8% 6% 27% 35% 20% 4	487
August	1st to 10th	Day	11% 7% 31% 33% 15% 3	447
	11th to 20th	Day	8% 10% 31% 32% 14% 4	437
	21st to end	Day	5% 6% 35% 36% 14% 4	495
September	1st to 10th	Day	10% 11% 32% 29% 17% 2	450
	11th to 20th	Day	6% 17% 41% 25% 8% 2	450
	21st to end	Day	7% 22% 29% 28% 11% 3	370
October	1st to 10th	Day	11% 24% 25% 22% 15% 3	270
	11th to 20th	Day	6% 25% 29% 27% 11% 1	270
	21st to end	Day	10% 25% 30% 25% 9% 1	297
November	1st to 10th	Day	11% 31% 27% 22% 8% 1	270
	11th to 20th	Day	6% 25% 33% 22% 13% 1	270
	21st to end	Day	8% 26% 30% 23% 11% 1	270
December	1st to 10th	Day	13% 24% 31% 22% 9% 1	270
	11th to 20th	Day	12% 24% 30% 23% 10% 1	270
	21st to end	Day	18% 22% 35% 19% 6% 1	297
January	1st to 10th	Night	8% 12% 30% 31% 15% 4	822
	11th to 20th	Night	8% 14% 30% 29% 16% 3	760
	21st to end	Night	5% 13% 30% 34% 14% 4	836
February	1st to 10th	Night	8% 17% 36% 29% 9% 2	760
	11th to 20th	Night	7% 17% 38% 27% 10% 1	744
	21st to end	Night	9% 18% 42% 24% 7%	628
March	1st to 10th	Night	9% 23% 32% 24% 10% 2	742
	11th to 20th	Night	5% 15% 32% 31% 17% 1	720
	21st to end	Night	8% 21% 32% 26% 10% 2	788
April	1st to 10th	Night	10% 20% 36% 27% 7% 1	540
	11th to 20th	Night	11% 20% 32% 27% 9% 1	533
	21st to end	Night	11% 18% 29% 27% 12% 3	540
May	1st to 10th	Night	6% 14% 37% 31% 12% 1	540
	11th to 20th	Night	8% 11% 29% 32% 16% 4	531
	21st to end	Night	8% 11% 32% 30% 17% 2	584
June	1st to 10th	Night	3 8% 27% 36% 24% 3	540
	11th to 20th	Night	3 12% 27% 37% 19% 3	540
	21st to end	Night	1 5% 23% 41% 26% 4	540
July	1st to 10th	Night	3 19% 38% 36% 3	525
	11th to 20th	Night	2 2 13% 40% 38% 6%	522
	21st to end	Night	3 3 7% 37% 45% 5%	591
August	1st to 10th	Night	4 3 12% 39% 38% 6%	537
	11th to 20th	Night	4 2 13% 41% 34% 5%	534
	21st to end	Night	4 3 15% 42% 29% 7%	594
September	1st to 10th	Night	4 3 18% 43% 28% 4	540
	11th to 20th	Night	3 4 22% 37% 29% 5%	547
	21st to end	Night	4 10% 21% 35% 21% 9%	720
October	1st to 10th	Night	7% 13% 27% 36% 16% 2	720
	11th to 20th	Night	4 11% 27% 32% 20% 5%	720
	21st to end	Night	9% 11% 26% 30% 19% 5%	792
November	1st to 10th	Night	6% 15% 25% 32% 18% 4	741
	11th to 20th	Night	7% 13% 32% 29% 16% 3	950
	21st to end	Night	8% 17% 27% 31% 14% 3	950
December	1st to 10th	Night	9% 14% 32% 31% 12% 2	950
	11th to 20th	Night	9% 19% 31% 25% 15% 1	950
	21st to end	Night	9% 13% 37% 31% 8% 1	1045

Page generated at 2024-03-03 04:29:00. Version ac07

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