Waltz Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waltz Road clear sky chart from 2005-11-06 to 2024-01-16.

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	8% 3 1 3 3 2 3 3 4 6% 64%	74759
	Night	11% 3 1 3 3 2 3 3 4 6% 61%	75053
Transparency	Day	23% 4 8% 19% 25% 21%	74474
	Night	26% 4 9% 19% 23% 19%	74859
Seeing	Day	9% 5% 16% 26% 30% 15%	14049
	Night	11% 3 16% 38% 28% 4	23460

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	24% 8% 2 4 4 3 4 5% 5% 6% 35%	1519
	11th to 20th	Day	16% 6% 3 4 4 3 4 3 4 5% 49%	1635
	21st to end	Day	15% 7% 2 4 5% 3 4 5% 5% 8% 41%	1782
February	1st to 10th	Day	18% 5% 2 4 4 2 4 3 4 7% 47%	1620
	11th to 20th	Day	14% 4 2 4 5% 2 3 4 4 8% 50%	1673
	21st to end	Day	16% 5% 2 4 4 2 2 3 5% 6% 51%	1480
March	1st to 10th	Day	16% 6% 3 5% 4 3 5% 5% 5% 7% 40%	1872
	11th to 20th	Day	19% 5% 2 5% 4 2 5% 4 6% 6% 42%	1980
	21st to end	Day	15% 5% 1 4 4 3 4 4 5% 7% 47%	2250
April	1st to 10th	Day	14% 5% 2 3 4 3 4 4 5% 7% 49%	2160
	11th to 20th	Day	11% 3 2 3 3 2 4 3 6% 6% 58%	2129
	21st to end	Day	6% 3 1 2 3 2 3 3 4 8% 64%	2160
May	1st to 10th	Day	5% 3 1 2 3 2 3 3 3 6% 69%	2218
	11th to 20th	Day	4 2 1 3 3 2 3 3 5% 7% 67%	2472
	21st to end	Day	5% 2 1 2 3 2 3 4 5% 8% 67%	2723
June	1st to 10th	Day	5% 2 1 2 2 2 3 3 4 7% 68%	2520
	11th to 20th	Day	2 1 1 1 1 1 2 2 3 4 82%	2520
	21st to end	Day	2 1 1 1 1 2 2 2 3 85%	2520
July	1st to 10th	Day	1 1 1 2 2 3 88%	2520
	11th to 20th	Day	1 1 1 1 1 1 1 2 3 88%	2516
	21st to end	Day	1 1 1 1 1 2 2 3 3 85%	2546
August	1st to 10th	Day	2 1 1 1 1 2 2 2 4 85%	2328
	11th to 20th	Day	1 1 1 1 1 1 2 2 4 86%	2173
	21st to end	Day	1 1 1 1 1 1 3 91%	2376
September	1st to 10th	Day	1 1 1 1 1 2 2 3 88%	2160
	11th to 20th	Day	3 1 1 1 3 1 2 3 3 5% 78%	2160
	21st to end	Day	4 2 1 2 2 1 1 2 3 4 80%	1935
October	1st to 10th	Day	3 2 1 3 3 2 3 2 3 5% 73%	1800
	11th to 20th	Day	6% 2 1 2 2 1 3 4 4 5% 71%	1800
	21st to end	Day	7% 3 1 3 3 2 3 3 4 5% 65%	1980
November	1st to 10th	Day	10% 3 2 3 3 2 5% 4 4 7% 57%	1724
	11th to 20th	Day	13% 4 2 3 5% 3 5% 4 5% 7% 51%	1710
	21st to end	Day	11% 4 2 4 4 2 4 3 5% 7% 54%	1556
December	1st to 10th	Day	15% 6% 2 5% 4 3 4 4 5% 6% 48%	1520
	11th to 20th	Day	29% 7% 4 6% 5% 2 3 4 4 5% 30%	1928
	21st to end	Day	17% 8% 3 6% 6% 4 5% 6% 6% 8% 32%	2794
January	1st to 10th	Night	20% 5% 2 5% 5% 2 4 3 5% 8% 41%	2646
	11th to 20th	Night	15% 5% 2 4 4 3 5% 4 5% 6% 47%	2434
	21st to end	Night	16% 4 2 4 5% 2 4 4 4 7% 47%	2574
February	1st to 10th	Night	17% 4 1 3 3 2 3 3 4 6% 52%	2340
	11th to 20th	Night	13% 4 2 3 4 2 4 4 5% 7% 52%	2174
	21st to end	Night	17% 5% 2 3 2 2 3 4 4 6% 52%	1776
March	1st to 10th	Night	18% 6% 3 6% 5% 3 4 4 4 6% 41%	2084
	11th to 20th	Night	18% 4 1 4 3 2 3 4 4 9% 47%	1980
	21st to end	Night	16% 3 2 3 5% 2 4 4 5% 7% 49%	2106
April	1st to 10th	Night	11% 5% 2 4 5% 2 4 4 5% 7% 51%	1800
	11th to 20th	Night	10% 3 2 3 3 2 2 4 4 8% 59%	1779
	21st to end	Night	6% 2 1 3 3 1 2 3 4 7% 67%	1800
May	1st to 10th	Night	6% 3 1 2 2 2 3 4 4 6% 68%	1738
	11th to 20th	Night	4 1 1 2 3 2 3 4 5% 8% 68%	1420
	21st to end	Night	5% 2 1 2 2 2 3 3 4 7% 69%	1552
June	1st to 10th	Night	5% 2 1 2 3 2 3 4 4 7% 69%	1440
	11th to 20th	Night	1 1 2 2 1 2 2 3 5% 81%	1440
	21st to end	Night	2 1 1 1 2 1 2 2 2 3 83%	1440
July	1st to 10th	Night	1 1 1 1 1 2 3 89%	1440
	11th to 20th	Night	1 1 1 1 1 1 1 1 2 89%	1440
	21st to end	Night	1 1 1 1 1 1 2 2 3 4 83%	1773
August	1st to 10th	Night	2 1 1 2 2 1 2 2 3 3 80%	1611
	11th to 20th	Night	1 1 1 1 1 2 2 3 4 84%	1726
	21st to end	Night	1 1 1 1 1 1 1 1 2 2 88%	1980
September	1st to 10th	Night	1 1 1 1 1 1 1 1 3 89%	1800
	11th to 20th	Night	4 2 1 2 1 2 1 2 3 4 79%	1800
	21st to end	Night	2 1 1 2 1 1 3 2 6% 80%	2022
October	1st to 10th	Night	5% 2 1 2 3 1 2 2 3 4 75%	2160
	11th to 20th	Night	5% 2 1 2 2 1 2 3 4 6% 73%	2160
	21st to end	Night	6% 2 1 2 3 2 2 3 3 6% 69%	2376
November	1st to 10th	Night	12% 3 2 3 3 2 3 3 5% 7% 57%	2352
	11th to 20th	Night	10% 3 2 3 4 2 3 5% 5% 7% 58%	2470
	21st to end	Night	11% 4 2 3 3 2 3 4 4 6% 58%	2622
December	1st to 10th	Night	18% 4 2 3 4 2 3 3 4 6% 51%	2660
	11th to 20th	Night	28% 7% 2 4 4 2 3 3 6% 7% 35%	3276
	21st to end	Night	20% 6% 2 6% 6% 4 5% 5% 5% 6% 35%	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	50% 6% 13% 18% 11% 3	1519
	11th to 20th	Day	39% 6% 10% 16% 18% 11%	1635
	21st to end	Day	42% 5% 10% 17% 19% 6%	1782
February	1st to 10th	Day	40% 3 10% 20% 19% 8%	1620
	11th to 20th	Day	34% 6% 9% 22% 22% 7%	1682
	21st to end	Day	37% 4 10% 23% 19% 7%	1480
March	1st to 10th	Day	44% 5% 11% 20% 15% 5%	1872
	11th to 20th	Day	42% 5% 9% 23% 16% 5%	1980
	21st to end	Day	37% 8% 13% 20% 18% 4	2250
April	1st to 10th	Day	36% 5% 10% 24% 18% 7%	2160
	11th to 20th	Day	27% 6% 11% 25% 24% 8%	2132
	21st to end	Day	20% 5% 13% 28% 27% 7%	2160
May	1st to 10th	Day	18% 3 11% 26% 30% 12%	2218
	11th to 20th	Day	18% 4 9% 29% 29% 12%	2475
	21st to end	Day	17% 6% 14% 31% 24% 9%	2724
June	1st to 10th	Day	18% 4 9% 27% 28% 14%	2520
	11th to 20th	Day	8% 2 8% 21% 33% 28%	2520
	21st to end	Day	7% 1 4 13% 37% 38%	2520
July	1st to 10th	Day	5% 2 3 10% 27% 54%	2451
	11th to 20th	Day	6% 1 3 12% 27% 52%	2441
	21st to end	Day	7% 1 3 8% 25% 56%	2405
August	1st to 10th	Day	8% 1 3 13% 30% 45%	2312
	11th to 20th	Day	6% 1 3 11% 33% 47%	2173
	21st to end	Day	4 1 2 12% 36% 46%	2376
September	1st to 10th	Day	5% 1 3 8% 30% 54%	2160
	11th to 20th	Day	12% 3 6% 21% 38% 21%	2160
	21st to end	Day	12% 2 4 20% 32% 30%	1935
October	1st to 10th	Day	15% 3 7% 18% 31% 27%	1800
	11th to 20th	Day	17% 3 7% 22% 24% 26%	1800
	21st to end	Day	22% 4 7% 20% 27% 20%	1980
November	1st to 10th	Day	27% 5% 8% 27% 22% 11%	1724
	11th to 20th	Day	34% 4 11% 24% 19% 7%	1710
	21st to end	Day	31% 4 11% 22% 21% 9%	1556
December	1st to 10th	Day	38% 7% 10% 21% 17% 8%	1520
	11th to 20th	Day	57% 4 8% 13% 14% 4	1928
	21st to end	Day	47% 9% 16% 16% 9% 3	2794
January	1st to 10th	Night	43% 5% 13% 23% 10% 6%	2646
	11th to 20th	Night	38% 5% 12% 17% 15% 13%	2434
	21st to end	Night	38% 4 12% 17% 20% 9%	2574
February	1st to 10th	Night	35% 3 8% 23% 21% 9%	2340
	11th to 20th	Night	32% 5% 9% 23% 23% 8%	2176
	21st to end	Night	34% 4 9% 23% 22% 9%	1776
March	1st to 10th	Night	44% 5% 10% 18% 17% 6%	2084
	11th to 20th	Night	37% 4 9% 22% 21% 7%	1980
	21st to end	Night	35% 6% 11% 22% 19% 7%	2106
April	1st to 10th	Night	33% 5% 12% 19% 23% 8%	1800
	11th to 20th	Night	26% 4 12% 27% 19% 12%	1779
	21st to end	Night	19% 4 13% 29% 26% 8%	1800
May	1st to 10th	Night	18% 5% 10% 23% 30% 14%	1738
	11th to 20th	Night	16% 4 11% 31% 24% 14%	1420
	21st to end	Night	16% 4 16% 30% 27% 8%	1552
June	1st to 10th	Night	17% 3 13% 26% 28% 12%	1440
	11th to 20th	Night	9% 2 8% 22% 33% 28%	1440
	21st to end	Night	9% 1 3 12% 33% 41%	1440
July	1st to 10th	Night	5% 1 2 10% 30% 53%	1400
	11th to 20th	Night	6% 3 10% 24% 57%	1392
	21st to end	Night	7% 1 3 10% 25% 54%	1674
August	1st to 10th	Night	11% 1 3 13% 29% 42%	1602
	11th to 20th	Night	6% 2 3 10% 32% 47%	1726
	21st to end	Night	6% 1 2 10% 32% 49%	1980
September	1st to 10th	Night	6% 1 2 8% 30% 54%	1800
	11th to 20th	Night	12% 1 6% 18% 38% 25%	1800
	21st to end	Night	9% 2 5% 18% 30% 36%	2022
October	1st to 10th	Night	16% 3 6% 17% 28% 31%	2160
	11th to 20th	Night	15% 4 6% 18% 27% 30%	2160
	21st to end	Night	18% 3 7% 21% 27% 25%	2376
November	1st to 10th	Night	28% 4 9% 23% 21% 16%	2352
	11th to 20th	Night	27% 4 12% 27% 21% 9%	2470
	21st to end	Night	29% 4 7% 24% 24% 12%	2622
December	1st to 10th	Night	36% 4 11% 21% 18% 10%	2660
	11th to 20th	Night	50% 5% 9% 17% 16% 4	3276
	21st to end	Night	49% 7% 14% 17% 10% 4	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	42% 4 12% 22% 17% 2	180
	11th to 20th	Day	21% 6% 17% 23% 23% 11%	325
	21st to end	Day	17% 6% 16% 25% 23% 13%	374
February	1st to 10th	Day	21% 7% 14% 21% 27% 11%	340
	11th to 20th	Day	19% 9% 23% 20% 18% 11%	379
	21st to end	Day	17% 10% 21% 24% 22% 5%	346
March	1st to 10th	Day	21% 10% 23% 25% 15% 5%	420
	11th to 20th	Day	22% 8% 23% 20% 18% 9%	420
	21st to end	Day	19% 10% 23% 24% 20% 5%	462
April	1st to 10th	Day	17% 7% 22% 26% 19% 9%	420
	11th to 20th	Day	12% 9% 26% 25% 17% 11%	412
	21st to end	Day	5% 9% 19% 29% 24% 15%	420
May	1st to 10th	Day	6% 8% 25% 25% 25% 11%	423
	11th to 20th	Day	7% 4 23% 26% 25% 15%	448
	21st to end	Day	5% 5% 17% 24% 27% 22%	485
June	1st to 10th	Day	4 4 20% 23% 33% 16%	450
	11th to 20th	Day	2 4 18% 28% 36% 11%	450
	21st to end	Day	1 2 12% 28% 40% 17%	450
July	1st to 10th	Day	1 9% 33% 44% 13%	446
	11th to 20th	Day	6% 30% 45% 19%	444
	21st to end	Day	1 1 9% 28% 41% 21%	487
August	1st to 10th	Day	2 1 9% 33% 37% 18%	447
	11th to 20th	Day	1 7% 30% 38% 23%	437
	21st to end	Day	1 7% 27% 43% 23%	495
September	1st to 10th	Day	2 1 6% 27% 43% 22%	450
	11th to 20th	Day	4 3 15% 26% 32% 20%	450
	21st to end	Day	3 2 17% 28% 28% 22%	450
October	1st to 10th	Day	3 6% 16% 23% 31% 21%	450
	11th to 20th	Day	6% 5% 13% 21% 33% 23%	450
	21st to end	Day	9% 6% 11% 24% 30% 18%	495
November	1st to 10th	Day	13% 4 14% 25% 29% 15%	320
	11th to 20th	Day	13% 3 14% 26% 33% 11%	270
	21st to end	Day	12% 1 18% 26% 34% 9%	196
December	1st to 10th	Day	22% 7% 15% 24% 21% 11%	180
	11th to 20th	Day	21% 4 16% 24% 23% 12%	180
	21st to end	Day	22% 9% 19% 23% 24% 3	198
January	1st to 10th	Night	23% 3 14% 32% 23% 6%	760
	11th to 20th	Night	17% 3 12% 38% 24% 5%	740
	21st to end	Night	19% 3 11% 37% 25% 5%	792
February	1st to 10th	Night	19% 3 13% 36% 25% 3	720
	11th to 20th	Night	16% 3 20% 34% 23% 4	704
	21st to end	Night	19% 6% 18% 38% 17% 4	592
March	1st to 10th	Night	20% 4 18% 32% 22% 4	720
	11th to 20th	Night	19% 4 17% 31% 25% 3	720
	21st to end	Night	17% 5% 22% 34% 22% 1	792
April	1st to 10th	Night	13% 3 22% 36% 23% 2	720
	11th to 20th	Night	11% 5% 23% 33% 24% 4	711
	21st to end	Night	8% 5% 19% 37% 28% 3	720
May	1st to 10th	Night	6% 3 26% 37% 24% 3	658
	11th to 20th	Night	5% 3 24% 41% 26% 2	358
	21st to end	Night	5% 5% 18% 45% 27% 1	389
June	1st to 10th	Night	5% 3 22% 42% 27% 1	360
	11th to 20th	Night	2 2 23% 49% 24% 1	360
	21st to end	Night	3 2 22% 41% 31% 1	360
July	1st to 10th	Night	1 1 19% 55% 24% 1	350
	11th to 20th	Night	1 1 17% 58% 23%	348
	21st to end	Night	1 1 16% 49% 32% 2	591
August	1st to 10th	Night	3 1 21% 46% 27% 1	537
	11th to 20th	Night	1 1 11% 49% 36% 2	658
	21st to end	Night	2 1 10% 47% 39% 2	792
September	1st to 10th	Night	2 1 9% 38% 47% 4	720
	11th to 20th	Night	4 2 15% 36% 39% 5%	720
	21st to end	Night	2 2 16% 35% 38% 8%	720
October	1st to 10th	Night	5% 4 12% 39% 32% 8%	720
	11th to 20th	Night	5% 2 13% 36% 38% 5%	720
	21st to end	Night	6% 3 13% 35% 32% 11%	792
November	1st to 10th	Night	12% 3 12% 31% 32% 9%	740
	11th to 20th	Night	11% 2 12% 42% 29% 5%	760
	21st to end	Night	12% 3 14% 38% 27% 6%	760
December	1st to 10th	Night	20% 4 13% 33% 23% 7%	760
	11th to 20th	Night	26% 3 13% 31% 24% 3	760
	21st to end	Night	23% 5% 16% 34% 19% 3	836

Page generated at 2024-01-12 22:38:09. Version ac07

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