Meadow View Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Meadow View Observatory clear sky chart from 2005-11-06 to 2024-11-02.

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	10% 3 1 3 2 2 2 2 3 5% 66%	101304
	Night	12% 4 1 3 2 2 3 2 4 5% 60%	97872
Transparency	Day	22% 4 8% 17% 23% 25%	101058
	Night	26% 5% 9% 17% 21% 22%	97707
Seeing	Day	10% 7% 18% 28% 27% 10%	15125
	Night	12% 4 17% 36% 27% 3	24330

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	27% 8% 2 5% 4 2 3 2 4 6% 37%	2539
	11th to 20th	Day	28% 8% 3 6% 4 3 3 2 4 4 35%	2778
	21st to end	Day	29% 7% 3 5% 3 2 3 3 4 7% 34%	3146
February	1st to 10th	Day	19% 5% 2 3 3 3 4 3 5% 5% 48%	1710
	11th to 20th	Day	17% 6% 2 5% 3 3 4 2 4 7% 48%	1726
	21st to end	Day	18% 5% 2 3 3 4 3 2 5% 7% 49%	1570
March	1st to 10th	Day	25% 10% 3 7% 4 3 3 3 4 6% 33%	3308
	11th to 20th	Day	16% 5% 1 3 2 2 2 2 4 6% 57%	3490
	21st to end	Day	19% 9% 2 5% 4 4 4 3 6% 7% 38%	3933
April	1st to 10th	Day	14% 6% 2 5% 4 3 4 3 5% 8% 48%	2280
	11th to 20th	Day	12% 4 2 4 3 2 2 4 5% 5% 57%	2249
	21st to end	Day	6% 3 2 3 2 3 3 3 4 8% 63%	2280
May	1st to 10th	Day	6% 2 1 2 2 2 2 2 3 5% 72%	4013
	11th to 20th	Day	3 2 1 2 1 1 1 2 3 5% 80%	4376
	21st to end	Day	3 2 1 2 2 2 2 2 4 5% 76%	4813
June	1st to 10th	Day	5% 3 1 2 2 2 3 3 5% 8% 64%	2660
	11th to 20th	Day	2 1 2 2 2 2 2 3 5% 79%	2660
	21st to end	Day	2 1 1 1 1 1 2 1 2 3 84%	2660
July	1st to 10th	Day	1 1 1 1 1 2 93%	4420
	11th to 20th	Day	1 1 1 1 1 1 1 2 3 86%	4420
	21st to end	Day	1 1 1 1 1 1 2 2 90%	4463
August	1st to 10th	Day	2 2 1 2 2 1 2 3 4 5% 77%	4091
	11th to 20th	Day	1 1 1 1 1 1 2 3 90%	3882
	21st to end	Day	1 1 1 1 1 1 1 1 2 2 89%	4180
September	1st to 10th	Day	1 1 1 1 1 1 1 2 3 88%	2280
	11th to 20th	Day	3 2 1 3 2 2 3 2 3 5% 76%	2280
	21st to end	Day	3 1 2 1 1 1 2 3 5% 81%	2024
October	1st to 10th	Day	4 2 3 2 2 2 2 3 4 75%	1900
	11th to 20th	Day	7% 3 1 3 2 2 2 2 4 5% 70%	1900
	21st to end	Day	10% 2 1 3 2 2 3 3 4 7% 62%	2090
November	1st to 10th	Day	14% 4 1 4 2 3 3 3 5% 7% 54%	1739
	11th to 20th	Day	15% 4 1 5% 3 3 4 3 5% 8% 50%	1682
	21st to end	Day	13% 4 1 4 3 3 4 3 5% 6% 55%	1520
December	1st to 10th	Day	20% 4 2 3 2 3 3 2 3 5% 52%	1520
	11th to 20th	Day	31% 8% 2 5% 4 4 3 2 3 5% 31%	1928
	21st to end	Day	23% 7% 2 6% 4 4 4 2 5% 7% 37%	2794
January	1st to 10th	Night	18% 7% 3 6% 4 3 3 3 5% 8% 41%	4406
	11th to 20th	Night	28% 5% 2 5% 3 3 3 3 5% 6% 37%	4172
	21st to end	Night	28% 8% 2 7% 4 4 3 3 3 6% 32%	4521
February	1st to 10th	Night	18% 4 1 4 3 3 3 3 5% 6% 49%	2470
	11th to 20th	Night	16% 5% 2 4 4 4 3 4 5% 7% 47%	2341
	21st to end	Night	16% 6% 1 4 4 3 3 3 4 6% 50%	1884
March	1st to 10th	Night	22% 9% 3 6% 4 3 3 3 4 6% 37%	3564
	11th to 20th	Night	18% 5% 1 3 2 1 2 2 3 6% 57%	3490
	21st to end	Night	19% 7% 3 6% 4 4 4 4 6% 6% 39%	3719
April	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 6% 8% 49%	1900
	11th to 20th	Night	11% 5% 1 4 3 3 3 2 5% 7% 57%	1879
	21st to end	Night	7% 4 2 3 2 2 3 3 4 6% 65%	1900
May	1st to 10th	Night	5% 4 2 4 3 2 2 3 4 5% 67%	2956
	11th to 20th	Night	2 2 1 2 2 2 3 2 3 5% 75%	2516
	21st to end	Night	3 3 1 2 2 2 2 2 3 5% 74%	2762
June	1st to 10th	Night	5% 3 1 4 3 3 3 3 5% 9% 61%	1520
	11th to 20th	Night	2 1 2 2 2 2 2 3 6% 78%	1520
	21st to end	Night	1 1 1 2 1 1 2 2 3 3 82%	1520
July	1st to 10th	Night	1 1 1 1 1 2 93%	2540
	11th to 20th	Night	1 2 1 2 1 1 1 1 2 2 85%	2540
	21st to end	Night	1 1 1 1 1 1 2 3 88%	3098
August	1st to 10th	Night	3 2 1 2 2 2 2 2 4 3 76%	2848
	11th to 20th	Night	1 1 1 1 1 2 2 91%	2962
	21st to end	Night	2 1 1 1 1 1 1 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 2 3 88%	1900
	11th to 20th	Night	3 2 1 2 2 2 2 2 3 5% 76%	1900
	21st to end	Night	3 1 1 1 1 2 1 4 5% 80%	2150
October	1st to 10th	Night	5% 2 1 2 2 1 2 2 3 3 76%	2280
	11th to 20th	Night	5% 2 1 2 2 2 3 2 4 4 73%	2280
	21st to end	Night	8% 2 1 3 2 2 3 2 4 6% 68%	2508
November	1st to 10th	Night	14% 4 1 3 2 3 3 3 5% 7% 54%	2374
	11th to 20th	Night	13% 4 1 3 3 3 3 4 6% 7% 53%	2496
	21st to end	Night	13% 5% 2 4 2 3 3 3 5% 6% 56%	2660
December	1st to 10th	Night	21% 5% 1 3 3 2 3 2 5% 7% 49%	2660
	11th to 20th	Night	33% 6% 2 3 3 3 3 3 4 6% 33%	3276
	21st to end	Night	24% 6% 2 6% 4 4 4 3 4 6% 37%	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	49% 6% 10% 26% 7% 3	2539
	11th to 20th	Day	53% 6% 8% 14% 10% 8%	2778
	21st to end	Day	51% 7% 12% 13% 12% 5%	3146
February	1st to 10th	Day	37% 6% 12% 18% 20% 8%	1710
	11th to 20th	Day	36% 6% 9% 20% 22% 7%	1735
	21st to end	Day	35% 5% 11% 26% 17% 6%	1570
March	1st to 10th	Day	50% 9% 9% 15% 13% 4	3308
	11th to 20th	Day	30% 4 9% 24% 21% 12%	3490
	21st to end	Day	41% 10% 13% 20% 12% 3	3933
April	1st to 10th	Day	35% 6% 11% 23% 19% 6%	2280
	11th to 20th	Day	29% 5% 11% 23% 23% 9%	2252
	21st to end	Day	20% 5% 13% 29% 24% 9%	2280
May	1st to 10th	Day	15% 4 11% 24% 25% 21%	4013
	11th to 20th	Day	11% 3 7% 22% 35% 23%	4379
	21st to end	Day	11% 4 12% 31% 28% 13%	4814
June	1st to 10th	Day	18% 6% 11% 25% 26% 15%	2660
	11th to 20th	Day	8% 3 9% 20% 32% 27%	2660
	21st to end	Day	8% 2 4 13% 32% 42%	2660
July	1st to 10th	Day	3 1 2 6% 16% 73%	4351
	11th to 20th	Day	7% 1 2 7% 18% 65%	4345
	21st to end	Day	3 1 1 6% 28% 60%	4322
August	1st to 10th	Day	10% 2 2 7% 26% 52%	4076
	11th to 20th	Day	4 1 1 10% 41% 43%	3921
	21st to end	Day	5% 1 3 14% 38% 39%	4179
September	1st to 10th	Day	4 1 3 8% 26% 57%	2280
	11th to 20th	Day	12% 3 6% 21% 36% 22%	2280
	21st to end	Day	10% 2 6% 20% 30% 33%	2024
October	1st to 10th	Day	15% 4 5% 17% 28% 31%	1900
	11th to 20th	Day	18% 3 7% 19% 24% 29%	1900
	21st to end	Day	21% 5% 7% 20% 28% 20%	2090
November	1st to 10th	Day	29% 5% 11% 22% 19% 14%	1739
	11th to 20th	Day	32% 8% 11% 22% 18% 9%	1682
	21st to end	Day	30% 6% 10% 20% 21% 13%	1520
December	1st to 10th	Day	36% 6% 9% 19% 20% 11%	1520
	11th to 20th	Day	58% 4 7% 13% 13% 5%	1928
	21st to end	Day	46% 9% 14% 17% 11% 3	2794
January	1st to 10th	Night	41% 9% 16% 22% 9% 3	4406
	11th to 20th	Night	48% 9% 11% 11% 13% 8%	4172
	21st to end	Night	55% 6% 10% 11% 13% 6%	4521
February	1st to 10th	Night	35% 5% 9% 21% 17% 13%	2470
	11th to 20th	Night	35% 6% 9% 19% 23% 9%	2343
	21st to end	Night	36% 5% 9% 23% 19% 8%	1884
March	1st to 10th	Night	43% 12% 15% 13% 14% 3	3564
	11th to 20th	Night	30% 5% 7% 23% 22% 12%	3490
	21st to end	Night	40% 10% 15% 20% 11% 4	3719
April	1st to 10th	Night	32% 6% 14% 21% 19% 9%	1900
	11th to 20th	Night	26% 6% 12% 25% 20% 11%	1879
	21st to end	Night	20% 6% 13% 27% 26% 8%	1900
May	1st to 10th	Night	16% 7% 11% 17% 29% 20%	2956
	11th to 20th	Night	12% 4 9% 19% 32% 25%	2516
	21st to end	Night	12% 6% 10% 33% 24% 16%	2762
June	1st to 10th	Night	19% 7% 12% 25% 25% 12%	1520
	11th to 20th	Night	9% 4 9% 19% 30% 29%	1520
	21st to end	Night	9% 2 4 13% 29% 42%	1520
July	1st to 10th	Night	3 1 2 7% 14% 74%	2500
	11th to 20th	Night	9% 1 2 6% 17% 65%	2492
	21st to end	Night	5% 1 1 7% 26% 60%	3001
August	1st to 10th	Night	14% 2 2 8% 24% 51%	2839
	11th to 20th	Night	4 2 2 9% 36% 48%	2989
	21st to end	Night	6% 1 2 11% 35% 44%	3498
September	1st to 10th	Night	5% 2 2 7% 27% 58%	1900
	11th to 20th	Night	12% 3 6% 17% 36% 26%	1900
	21st to end	Night	9% 2 5% 16% 31% 37%	2150
October	1st to 10th	Night	15% 3 5% 16% 27% 34%	2280
	11th to 20th	Night	15% 4 7% 17% 27% 30%	2280
	21st to end	Night	18% 4 7% 21% 25% 25%	2508
November	1st to 10th	Night	28% 6% 10% 22% 17% 15%	2374
	11th to 20th	Night	28% 7% 13% 22% 19% 10%	2496
	21st to end	Night	30% 5% 7% 22% 22% 13%	2660
December	1st to 10th	Night	36% 5% 11% 18% 18% 12%	2660
	11th to 20th	Night	51% 5% 8% 14% 17% 5%	3276
	21st to end	Night	47% 8% 11% 17% 12% 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% 8% 13% 22% 14% 1	180
	11th to 20th	Day	24% 9% 18% 28% 14% 6%	327
	21st to end	Day	23% 5% 20% 23% 22% 7%	407
February	1st to 10th	Day	23% 9% 18% 26% 19% 5%	370
	11th to 20th	Day	22% 13% 21% 23% 16% 4	394
	21st to end	Day	16% 12% 25% 27% 16% 3	382
March	1st to 10th	Day	25% 17% 25% 20% 10% 2	460
	11th to 20th	Day	24% 10% 22% 23% 16% 5%	460
	21st to end	Day	21% 16% 24% 25% 12% 2	506
April	1st to 10th	Day	17% 14% 24% 25% 15% 4	460
	11th to 20th	Day	15% 13% 23% 24% 19% 6%	452
	21st to end	Day	6% 12% 21% 31% 24% 6%	460
May	1st to 10th	Day	8% 9% 34% 25% 20% 5%	463
	11th to 20th	Day	8% 9% 21% 25% 25% 12%	488
	21st to end	Day	4 8% 19% 27% 30% 12%	529
June	1st to 10th	Day	5% 7% 18% 28% 32% 10%	490
	11th to 20th	Day	4 6% 20% 34% 29% 7%	490
	21st to end	Day	1 3 15% 35% 33% 13%	490
July	1st to 10th	Day	1 2 10% 36% 39% 12%	486
	11th to 20th	Day	1 8% 33% 43% 14%	484
	21st to end	Day	1 6% 34% 45% 14%	531
August	1st to 10th	Day	2 1 12% 30% 40% 15%	487
	11th to 20th	Day	1 2 10% 27% 41% 18%	477
	21st to end	Day	2 1 9% 29% 45% 15%	539
September	1st to 10th	Day	1 2 10% 31% 43% 14%	490
	11th to 20th	Day	4 4 18% 28% 32% 14%	490
	21st to end	Day	3 4 19% 34% 30% 11%	490
October	1st to 10th	Day	4 7% 20% 25% 30% 15%	490
	11th to 20th	Day	8% 6% 18% 24% 31% 14%	490
	21st to end	Day	12% 7% 20% 28% 24% 10%	539
November	1st to 10th	Day	16% 7% 17% 22% 25% 12%	329
	11th to 20th	Day	14% 5% 14% 30% 25% 12%	257
	21st to end	Day	12% 6% 19% 29% 27% 7%	180
December	1st to 10th	Day	25% 6% 21% 22% 14% 13%	180
	11th to 20th	Day	27% 4 20% 24% 17% 8%	180
	21st to end	Day	20% 9% 20% 25% 22% 4	198
January	1st to 10th	Night	22% 5% 17% 34% 20% 2	760
	11th to 20th	Night	22% 5% 14% 39% 18% 2	760
	21st to end	Night	20% 4 19% 34% 20% 3	836
February	1st to 10th	Night	20% 4 17% 38% 19% 2	760
	11th to 20th	Night	18% 7% 18% 33% 21% 2	744
	21st to end	Night	18% 6% 24% 36% 14% 1	628
March	1st to 10th	Night	22% 10% 20% 29% 16% 3	760
	11th to 20th	Night	20% 7% 19% 29% 23% 2	760
	21st to end	Night	19% 9% 24% 32% 16% 1	836
April	1st to 10th	Night	12% 8% 28% 34% 18% 2	760
	11th to 20th	Night	12% 7% 23% 33% 21% 3	751
	21st to end	Night	8% 6% 22% 37% 24% 3	760
May	1st to 10th	Night	7% 7% 30% 32% 23% 1	627
	11th to 20th	Night	5% 3 22% 40% 28% 2	374
	21st to end	Night	5% 8% 18% 40% 27% 1	411
June	1st to 10th	Night	7% 3 19% 43% 27% 2	380
	11th to 20th	Night	1 4 22% 48% 24% 1	380
	21st to end	Night	2 2 17% 46% 31% 2	380
July	1st to 10th	Night	1 11% 48% 36% 2	370
	11th to 20th	Night	1 1 13% 50% 34% 2	368
	21st to end	Night	1 7% 39% 49% 4	613
August	1st to 10th	Night	2 2 9% 38% 47% 3	567
	11th to 20th	Night	1 1 9% 42% 44% 5%	649
	21st to end	Night	1 1 6% 38% 51% 3	836
September	1st to 10th	Night	1 1 8% 38% 48% 4	760
	11th to 20th	Night	4 2 11% 39% 38% 7%	760
	21st to end	Night	4 3 14% 36% 36% 8%	760
October	1st to 10th	Night	5% 4 17% 35% 33% 6%	760
	11th to 20th	Night	7% 3 15% 34% 36% 5%	760
	21st to end	Night	9% 4 15% 36% 29% 7%	836
November	1st to 10th	Night	15% 6% 14% 31% 30% 4	748
	11th to 20th	Night	14% 2 18% 39% 25% 2	760
	21st to end	Night	13% 4 17% 40% 23% 3	760
December	1st to 10th	Night	22% 4 15% 35% 21% 4	760
	11th to 20th	Night	28% 4 16% 30% 20% 2	760
	21st to end	Night	23% 6% 20% 34% 17% 1	836

Page generated at 2024-10-30 10:19:25. Version ac07

Copyright © 2024 Attilla Danko.