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 2024-12-06.

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	8% 3 1 3 2 2 3 2 4 5% 66%	105406
	Night	10% 4 1 4 3 3 3 2 4 5% 62%	103032
Transparency	Day	22% 3 7% 18% 24% 25%	105160
	Night	26% 3 8% 19% 22% 22%	102867
Seeing	Day	9% 5% 16% 26% 29% 15%	15270
	Night	11% 3 16% 38% 28% 4	24593

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	26% 9% 2 5% 4 4 4 3 4 6% 33%	2539
	11th to 20th	Day	24% 10% 4 8% 4 3 4 2 3 4 33%	2803
	21st to end	Day	24% 9% 3 7% 5% 4 4 3 5% 6% 29%	3146
February	1st to 10th	Day	18% 6% 2 5% 3 3 3 3 5% 6% 45%	1710
	11th to 20th	Day	15% 4 2 4 5% 3 3 3 4 7% 48%	1768
	21st to end	Day	16% 5% 1 4 4 3 3 3 5% 6% 50%	1570
March	1st to 10th	Day	17% 10% 4 8% 5% 4 5% 5% 5% 5% 32%	3262
	11th to 20th	Day	14% 4 1 4 2 3 3 2 5% 6% 57%	3490
	21st to end	Day	16% 7% 2 6% 4 4 5% 4 6% 7% 39%	3948
April	1st to 10th	Day	13% 6% 2 4 4 3 4 4 5% 7% 49%	2280
	11th to 20th	Day	10% 3 1 3 3 3 3 3 6% 6% 57%	2249
	21st to end	Day	6% 3 1 2 3 2 3 3 5% 8% 64%	2280
May	1st to 10th	Day	6% 2 1 1 1 2 2 2 3 5% 76%	3910
	11th to 20th	Day	2 1 1 2 2 2 2 2 3 4 80%	4372
	21st to end	Day	3 1 2 2 2 2 2 3 6% 77%	4813
June	1st to 10th	Day	5% 3 1 3 2 3 2 2 5% 7% 68%	2660
	11th to 20th	Day	1 1 1 1 1 1 2 2 3 4 82%	2660
	21st to end	Day	2 1 1 1 2 2 1 2 3 85%	2660
July	1st to 10th	Day	1 1 1 1 2 93%	4420
	11th to 20th	Day	1 1 1 1 1 1 2 2 3 86%	4403
	21st to end	Day	1 1 1 2 1 2 3 88%	4455
August	1st to 10th	Day	2 1 1 2 1 2 2 2 3 5% 80%	4091
	11th to 20th	Day	1 1 1 1 1 1 2 3 89%	3811
	21st to end	Day	1 1 1 1 1 1 1 1 2 90%	4180
September	1st to 10th	Day	1 1 1 1 1 1 2 3 89%	2280
	11th to 20th	Day	3 1 1 2 2 2 2 2 3 5% 77%	2280
	21st to end	Day	3 2 1 2 1 1 1 2 3 4 81%	2042
October	1st to 10th	Day	2 1 1 2 2 2 2 2 4 6% 76%	3180
	11th to 20th	Day	4 2 1 3 2 2 3 2 4 5% 72%	3161
	21st to end	Day	4 2 1 4 3 4 4 3 4 6% 65%	3448
November	1st to 10th	Day	10% 3 1 3 3 3 4 3 4 7% 58%	1816
	11th to 20th	Day	13% 4 2 4 4 4 4 3 4 7% 50%	1800
	21st to end	Day	12% 4 2 4 4 3 4 2 5% 7% 53%	1637
December	1st to 10th	Day	14% 6% 1 6% 3 4 4 3 5% 6% 48%	1560
	11th to 20th	Day	29% 8% 3 7% 4 3 3 3 4 5% 30%	1928
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 5% 6% 8% 31%	2794
January	1st to 10th	Night	16% 8% 3 8% 4 4 3 3 5% 7% 39%	4406
	11th to 20th	Night	23% 7% 3 7% 4 4 4 3 4 5% 35%	4163
	21st to end	Night	24% 8% 3 7% 5% 4 3 3 4 6% 33%	4521
February	1st to 10th	Night	17% 5% 2 4 3 3 3 3 4 6% 51%	2470
	11th to 20th	Night	14% 5% 2 4 3 4 3 3 6% 7% 50%	2299
	21st to end	Night	16% 5% 2 4 2 3 3 3 4 6% 52%	1884
March	1st to 10th	Night	21% 9% 3 7% 4 4 4 3 4 6% 35%	3595
	11th to 20th	Night	16% 4 1 3 2 2 2 2 3 5% 58%	3490
	21st to end	Night	18% 5% 2 6% 5% 4 4 4 6% 7% 39%	3692
April	1st to 10th	Night	10% 6% 2 4 4 3 4 3 5% 7% 52%	1900
	11th to 20th	Night	10% 4 1 3 3 3 2 3 4 7% 58%	1879
	21st to end	Night	6% 3 1 3 3 2 2 3 4 6% 67%	1900
May	1st to 10th	Night	4 2 2 2 2 3 3 4 6% 72%	3062
	11th to 20th	Night	2 1 1 1 1 1 2 2 3 5% 81%	2520
	21st to end	Night	3 1 1 1 1 1 2 1 2 5% 81%	2762
June	1st to 10th	Night	5% 2 1 2 3 3 3 3 4 7% 68%	1520
	11th to 20th	Night	1 1 2 2 1 1 1 3 5% 81%	1520
	21st to end	Night	2 1 1 1 1 1 2 2 2 3 83%	1520
July	1st to 10th	Night	1 1 1 2 94%	2540
	11th to 20th	Night	1 1 1 2 2 2 1 1 2 2 85%	2554
	21st to end	Night	1 1 1 1 2 1 3 4 87%	3109
August	1st to 10th	Night	3 2 1 2 1 2 2 2 4 5% 76%	2848
	11th to 20th	Night	1 1 1 1 2 3 90%	3033
	21st to end	Night	2 1 1 1 1 1 1 1 2 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 1 3 89%	1900
	11th to 20th	Night	3 2 1 2 1 2 1 1 3 4 78%	1900
	21st to end	Night	2 1 1 1 2 1 2 2 5% 81%	2135
October	1st to 10th	Night	3 2 1 2 2 2 2 2 3 3 79%	3800
	11th to 20th	Night	3 1 1 2 1 2 2 2 3 5% 78%	3777
	21st to end	Night	6% 2 1 3 2 3 3 3 4 6% 66%	4121
November	1st to 10th	Night	11% 3 1 4 3 3 3 3 5% 7% 57%	2480
	11th to 20th	Night	10% 3 1 3 3 3 3 4 5% 7% 57%	2600
	21st to end	Night	12% 4 2 3 3 3 3 3 4 6% 57%	2760
December	1st to 10th	Night	17% 4 2 4 3 3 3 2 4 6% 51%	2736
	11th to 20th	Night	28% 7% 2 4 3 3 3 3 6% 7% 35%	3276
	21st to end	Night	20% 6% 2 7% 5% 5% 5% 4 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	52% 7% 10% 22% 7% 2	2539
	11th to 20th	Day	57% 6% 8% 12% 11% 6%	2803
	21st to end	Day	56% 5% 10% 15% 11% 3	3146
February	1st to 10th	Day	41% 3 10% 20% 18% 8%	1710
	11th to 20th	Day	36% 6% 9% 21% 21% 7%	1777
	21st to end	Day	36% 5% 10% 24% 19% 6%	1570
March	1st to 10th	Day	52% 7% 10% 15% 13% 3	3262
	11th to 20th	Day	29% 5% 9% 29% 17% 12%	3490
	21st to end	Day	41% 8% 14% 22% 12% 2	3948
April	1st to 10th	Day	35% 5% 10% 25% 18% 7%	2280
	11th to 20th	Day	27% 6% 12% 25% 23% 7%	2252
	21st to end	Day	19% 5% 13% 29% 27% 7%	2280
May	1st to 10th	Day	15% 2 9% 27% 27% 20%	3910
	11th to 20th	Day	10% 3 5% 25% 39% 18%	4375
	21st to end	Day	11% 4 10% 34% 30% 12%	4814
June	1st to 10th	Day	18% 4 9% 27% 29% 14%	2660
	11th to 20th	Day	8% 2 8% 20% 34% 28%	2660
	21st to end	Day	7% 1 3 12% 37% 39%	2660
July	1st to 10th	Day	3 1 2 6% 15% 74%	4351
	11th to 20th	Day	7% 1 2 7% 17% 66%	4328
	21st to end	Day	4 1 2 6% 26% 62%	4315
August	1st to 10th	Day	10% 1 2 8% 24% 55%	4076
	11th to 20th	Day	4 1 1 8% 39% 47%	3849
	21st to end	Day	6% 1 2 11% 40% 41%	4179
September	1st to 10th	Day	5% 1 3 7% 30% 55%	2280
	11th to 20th	Day	12% 3 6% 21% 38% 20%	2280
	21st to end	Day	11% 1 4 20% 33% 31%	2042
October	1st to 10th	Day	12% 2 4 12% 26% 44%	3180
	11th to 20th	Day	16% 2 5% 25% 33% 20%	3161
	21st to end	Day	21% 3 8% 21% 32% 15%	3448
November	1st to 10th	Day	26% 5% 8% 27% 22% 11%	1816
	11th to 20th	Day	35% 4 11% 24% 19% 7%	1800
	21st to end	Day	32% 4 11% 22% 21% 10%	1637
December	1st to 10th	Day	38% 7% 10% 22% 16% 8%	1560
	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	44% 7% 14% 24% 8% 3	4406
	11th to 20th	Night	51% 5% 12% 12% 11% 8%	4163
	21st to end	Night	54% 4 12% 14% 12% 5%	4521
February	1st to 10th	Night	37% 3 9% 22% 20% 9%	2470
	11th to 20th	Night	33% 4 9% 23% 22% 8%	2301
	21st to end	Night	33% 4 9% 24% 21% 8%	1884
March	1st to 10th	Night	50% 7% 11% 14% 14% 4	3595
	11th to 20th	Night	30% 4 8% 25% 20% 14%	3490
	21st to end	Night	42% 7% 12% 23% 12% 4	3692
April	1st to 10th	Night	32% 5% 12% 20% 23% 8%	1900
	11th to 20th	Night	26% 4 12% 28% 18% 11%	1879
	21st to end	Night	19% 4 13% 30% 26% 8%	1900
May	1st to 10th	Night	15% 4 13% 22% 27% 20%	3062
	11th to 20th	Night	9% 3 7% 26% 41% 15%	2520
	21st to end	Night	9% 2 12% 39% 26% 11%	2762
June	1st to 10th	Night	17% 3 13% 27% 28% 12%	1520
	11th to 20th	Night	8% 2 7% 21% 34% 28%	1520
	21st to end	Night	9% 1 3 12% 32% 43%	1520
July	1st to 10th	Night	3 1 1 6% 17% 73%	2500
	11th to 20th	Night	9% 1 1 6% 16% 67%	2506
	21st to end	Night	5% 1 2 6% 28% 59%	3011
August	1st to 10th	Night	12% 1 2 8% 27% 50%	2839
	11th to 20th	Night	4 1 2 8% 38% 47%	3061
	21st to end	Night	7% 1 2 9% 36% 46%	3498
September	1st to 10th	Night	5% 1 2 7% 29% 55%	1900
	11th to 20th	Night	13% 1 6% 19% 38% 24%	1900
	21st to end	Night	8% 2 5% 18% 31% 36%	2135
October	1st to 10th	Night	13% 2 3 10% 20% 52%	3800
	11th to 20th	Night	12% 2 6% 27% 29% 23%	3777
	21st to end	Night	20% 2 5% 21% 31% 21%	4121
November	1st to 10th	Night	27% 4 9% 23% 21% 16%	2480
	11th to 20th	Night	27% 4 13% 27% 21% 9%	2600
	21st to end	Night	30% 4 7% 24% 24% 12%	2760
December	1st to 10th	Night	35% 4 11% 22% 18% 10%	2736
	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% 5% 18% 23% 23% 11%	339
	21st to end	Day	18% 6% 16% 25% 23% 12%	407
February	1st to 10th	Day	21% 7% 15% 22% 26% 10%	370
	11th to 20th	Day	19% 9% 24% 20% 17% 11%	414
	21st to end	Day	17% 9% 20% 27% 22% 5%	382
March	1st to 10th	Day	22% 11% 23% 25% 15% 5%	460
	11th to 20th	Day	20% 9% 23% 20% 18% 10%	460
	21st to end	Day	19% 10% 23% 25% 19% 4	506
April	1st to 10th	Day	16% 7% 22% 27% 19% 10%	460
	11th to 20th	Day	12% 8% 25% 25% 18% 12%	452
	21st to end	Day	5% 8% 19% 28% 23% 16%	460
May	1st to 10th	Day	7% 8% 26% 25% 24% 11%	463
	11th to 20th	Day	7% 4 22% 26% 26% 16%	488
	21st to end	Day	5% 5% 16% 25% 27% 22%	529
June	1st to 10th	Day	4 4 19% 25% 32% 16%	490
	11th to 20th	Day	2 4 17% 28% 37% 12%	490
	21st to end	Day	1 2 11% 29% 40% 17%	490
July	1st to 10th	Day	1 9% 31% 43% 15%	486
	11th to 20th	Day	1 6% 29% 44% 20%	484
	21st to end	Day	1 1 8% 28% 42% 20%	531
August	1st to 10th	Day	2 1 8% 32% 39% 18%	487
	11th to 20th	Day	1 1 8% 32% 37% 21%	477
	21st to end	Day	1 1 7% 26% 41% 24%	539
September	1st to 10th	Day	1 1 7% 27% 41% 22%	490
	11th to 20th	Day	4 2 16% 27% 31% 20%	490
	21st to end	Day	3 2 16% 27% 30% 22%	490
October	1st to 10th	Day	3 6% 15% 23% 33% 21%	490
	11th to 20th	Day	6% 4 14% 21% 31% 23%	490
	21st to end	Day	9% 6% 13% 26% 30% 17%	539
November	1st to 10th	Day	12% 4 16% 25% 28% 16%	352
	11th to 20th	Day	14% 2 14% 29% 31% 10%	300
	21st to end	Day	14% 1 18% 24% 34% 9%	217
December	1st to 10th	Day	21% 7% 14% 24% 21% 14%	190
	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	18% 3 12% 38% 24% 5%	760
	21st to end	Night	19% 3 11% 37% 25% 5%	836
February	1st to 10th	Night	20% 4 14% 35% 24% 3	760
	11th to 20th	Night	17% 4 19% 34% 23% 4	744
	21st to end	Night	18% 6% 18% 38% 17% 4	628
March	1st to 10th	Night	20% 5% 18% 32% 21% 3	760
	11th to 20th	Night	19% 5% 18% 31% 25% 3	760
	21st to end	Night	17% 5% 22% 34% 21% 1	836
April	1st to 10th	Night	13% 3 23% 37% 23% 2	760
	11th to 20th	Night	11% 5% 22% 33% 24% 4	751
	21st to end	Night	8% 5% 19% 37% 28% 3	760
May	1st to 10th	Night	6% 4 27% 36% 24% 3	694
	11th to 20th	Night	4 3 24% 43% 25% 2	378
	21st to end	Night	5% 5% 18% 45% 27% 1	411
June	1st to 10th	Night	5% 2 23% 42% 26% 1	380
	11th to 20th	Night	2 2 23% 49% 24% 1	380
	21st to end	Night	2 2 22% 43% 30% 1	380
July	1st to 10th	Night	1 1 18% 55% 25% 1	370
	11th to 20th	Night	1 1 18% 57% 24%	369
	21st to end	Night	1 1 16% 49% 31% 2	624
August	1st to 10th	Night	3 1 20% 48% 26% 1	567
	11th to 20th	Night	1 1 12% 50% 34% 2	695
	21st to end	Night	2 10% 46% 39% 2	836
September	1st to 10th	Night	1 1 9% 38% 46% 4	760
	11th to 20th	Night	4 2 15% 36% 38% 5%	760
	21st to end	Night	2 1 16% 35% 38% 7%	760
October	1st to 10th	Night	5% 4 11% 39% 33% 8%	760
	11th to 20th	Night	5% 3 14% 36% 38% 5%	760
	21st to end	Night	6% 3 13% 36% 31% 10%	836
November	1st to 10th	Night	12% 3 13% 31% 32% 8%	780
	11th to 20th	Night	11% 2 13% 42% 29% 4	800
	21st to end	Night	13% 3 14% 38% 26% 6%	800
December	1st to 10th	Night	19% 4 13% 33% 24% 8%	782
	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 2024-12-03 03:45:09. Version ac07

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