Monswath observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monswath observatory clear sky chart from 2005-11-06 to 2024-11-04.

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	12% 8% 3 6% 4 4 4 4 6% 8% 42%	101229
	Night	13% 8% 3 7% 4 4 4 3 5% 6% 43%	97830
Transparency	Day	38% 7% 12% 24% 17% 2	104863
	Night	39% 6% 11% 24% 18% 3	102337
Seeing	Day	15% 11% 28% 26% 15% 4	15651
	Night	16% 11% 30% 29% 12% 1	25453

By Month

Percentage Cloud Cover SE (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	10% 13% 5% 11% 6% 4 5% 4 5% 6% 31%	2527
	11th to 20th	Day	12% 11% 3 8% 6% 7% 5% 3 5% 5% 34%	2795
	21st to end	Day	18% 16% 7% 8% 4 3 3 3 4 5% 28%	3135
February	1st to 10th	Day	14% 12% 4 8% 4 5% 4 3 4 6% 34%	1710
	11th to 20th	Day	13% 11% 4 5% 5% 5% 4 3 5% 6% 38%	1780
	21st to end	Day	13% 13% 3 8% 4 4 4 3 4 6% 39%	1570
March	1st to 10th	Day	17% 12% 3 6% 4 3 3 3 3 4 42%	3248
	11th to 20th	Day	12% 8% 2 5% 3 4 3 3 5% 6% 49%	3480
	21st to end	Day	16% 10% 3 8% 5% 5% 4 4 6% 7% 32%	3963
April	1st to 10th	Day	12% 7% 3 7% 6% 4 5% 4 5% 8% 42%	2280
	11th to 20th	Day	17% 9% 3 6% 4 4 4 3 5% 5% 41%	2254
	21st to end	Day	18% 8% 2 7% 4 4 4 4 6% 7% 36%	2280
May	1st to 10th	Day	13% 8% 3 8% 5% 5% 5% 5% 7% 9% 32%	3851
	11th to 20th	Day	16% 9% 3 7% 4 4 5% 3 5% 7% 37%	4399
	21st to end	Day	10% 6% 2 6% 5% 4 4 3 6% 7% 46%	4824
June	1st to 10th	Day	7% 5% 2 5% 4 5% 5% 4 8% 9% 46%	2660
	11th to 20th	Day	8% 5% 1 4 4 4 4 4 6% 9% 50%	2660
	21st to end	Day	5% 4 2 5% 5% 5% 5% 6% 8% 9% 47%	2660
July	1st to 10th	Day	13% 6% 2 6% 4 4 4 4 7% 10% 40%	4440
	11th to 20th	Day	5% 4 2 5% 4 4 5% 4 7% 10% 50%	4440
	21st to end	Day	6% 5% 2 6% 6% 6% 6% 6% 7% 11% 39%	4480
August	1st to 10th	Day	6% 3 1 6% 4 4 5% 5% 7% 10% 50%	4104
	11th to 20th	Day	13% 5% 2 5% 5% 4 5% 4 6% 9% 42%	3794
	21st to end	Day	5% 5% 1 5% 4 4 4 4 7% 9% 51%	4180
September	1st to 10th	Day	12% 5% 2 4 4 3 3 3 6% 8% 50%	2280
	11th to 20th	Day	9% 6% 1 5% 4 3 4 4 6% 8% 50%	2280
	21st to end	Day	8% 5% 2 6% 4 3 4 4 5% 8% 52%	2036
October	1st to 10th	Day	10% 5% 2 5% 3 3 4 3 5% 6% 56%	1900
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 4 5% 53%	1900
	21st to end	Day	16% 8% 2 6% 3 3 3 3 4 6% 46%	2090
November	1st to 10th	Day	11% 6% 2 4 3 3 3 3 4 6% 55%	1720
	11th to 20th	Day	14% 7% 4 5% 3 3 4 3 5% 6% 46%	1710
	21st to end	Day	16% 10% 3 7% 4 3 3 3 4 6% 43%	1578
December	1st to 10th	Day	12% 13% 2 7% 4 3 3 4 4 7% 40%	1520
	11th to 20th	Day	14% 10% 3 7% 4 4 4 3 5% 7% 40%	1918
	21st to end	Day	18% 13% 5% 11% 5% 5% 5% 4 5% 5% 25%	2783
January	1st to 10th	Night	13% 11% 7% 11% 5% 4 4 3 4 4 35%	4428
	11th to 20th	Night	13% 11% 5% 12% 5% 6% 6% 4 4 5% 30%	4170
	21st to end	Night	22% 16% 6% 8% 4 3 3 3 3 4 28%	4532
February	1st to 10th	Night	14% 13% 4 8% 5% 4 4 3 5% 6% 34%	2470
	11th to 20th	Night	14% 8% 3 8% 5% 4 4 3 5% 6% 41%	2285
	21st to end	Night	16% 10% 3 7% 4 3 3 3 5% 4 41%	1884
March	1st to 10th	Night	21% 12% 2 5% 3 3 3 2 4 4 43%	3619
	11th to 20th	Night	13% 7% 2 5% 4 3 3 3 4 6% 50%	3480
	21st to end	Night	16% 12% 4 9% 5% 4 4 3 5% 5% 32%	3666
April	1st to 10th	Night	11% 7% 3 6% 5% 4 4 3 6% 7% 46%	1900
	11th to 20th	Night	13% 7% 3 7% 4 4 3 3 5% 6% 45%	1875
	21st to end	Night	18% 8% 2 5% 4 3 4 3 4 6% 42%	1900
May	1st to 10th	Night	17% 8% 3 5% 4 3 3 3 6% 9% 39%	3029
	11th to 20th	Night	14% 7% 2 8% 4 4 4 3 5% 8% 41%	2506
	21st to end	Night	9% 6% 2 6% 4 4 4 4 7% 10% 44%	2743
June	1st to 10th	Night	7% 4 2 5% 4 4 4 5% 7% 8% 51%	1520
	11th to 20th	Night	6% 5% 1 4 5% 4 5% 4 6% 8% 53%	1520
	21st to end	Night	4 4 1 4 4 5% 4 5% 6% 10% 53%	1520
July	1st to 10th	Night	12% 6% 2 7% 4 4 4 3 6% 9% 45%	2530
	11th to 20th	Night	4 3 1 4 3 3 4 3 7% 11% 57%	2530
	21st to end	Night	7% 5% 2 7% 5% 5% 5% 4 6% 11% 43%	3065
August	1st to 10th	Night	5% 3 2 4 3 4 3 3 6% 8% 59%	2836
	11th to 20th	Night	11% 6% 2 6% 3 3 4 3 4 7% 49%	3037
	21st to end	Night	5% 3 2 4 3 3 4 4 6% 10% 56%	3476
September	1st to 10th	Night	13% 4 2 4 3 2 3 3 5% 7% 55%	1900
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 6% 7% 53%	1900
	21st to end	Night	8% 5% 1 5% 4 4 4 3 5% 6% 55%	2122
October	1st to 10th	Night	8% 4 2 4 3 3 4 2 4 7% 59%	2280
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 4 6% 53%	2280
	21st to end	Night	16% 8% 2 5% 3 3 4 3 3 5% 47%	2508
November	1st to 10th	Night	10% 5% 2 5% 3 3 4 4 5% 5% 56%	2428
	11th to 20th	Night	13% 6% 2 5% 4 3 3 3 4 7% 49%	2470
	21st to end	Night	16% 10% 3 5% 4 4 3 3 4 5% 44%	2598
December	1st to 10th	Night	13% 11% 4 7% 5% 5% 5% 3 6% 6% 35%	2660
	11th to 20th	Night	15% 10% 4 8% 4 4 3 3 5% 6% 39%	3279
	21st to end	Night	17% 20% 6% 10% 6% 5% 4 3 4 4 23%	4884

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	51% 7% 11% 21% 9% 1	2528
	11th to 20th	Day	50% 6% 13% 20% 11%	2795
	21st to end	Day	58% 4 10% 15% 11% 1	3135
February	1st to 10th	Day	51% 5% 12% 21% 10% 1	1710
	11th to 20th	Day	46% 5% 11% 20% 15% 3	1789
	21st to end	Day	47% 5% 8% 21% 13% 4	1570
March	1st to 10th	Day	46% 5% 7% 20% 18% 3	3248
	11th to 20th	Day	35% 6% 13% 25% 17% 5%	3480
	21st to end	Day	47% 10% 15% 20% 7%	3963
April	1st to 10th	Day	41% 6% 11% 25% 16% 1	2280
	11th to 20th	Day	44% 5% 10% 23% 14% 3	2254
	21st to end	Day	46% 6% 12% 20% 14% 1	2280
May	1st to 10th	Day	43% 11% 15% 21% 10% 1	3886
	11th to 20th	Day	45% 8% 10% 24% 12% 1	4403
	21st to end	Day	35% 9% 11% 23% 21% 1	4837
June	1st to 10th	Day	31% 9% 15% 28% 16% 2	2660
	11th to 20th	Day	29% 7% 15% 26% 21% 4	2660
	21st to end	Day	29% 10% 16% 25% 15% 5%	2660
July	1st to 10th	Day	39% 6% 13% 27% 12% 2	4371
	11th to 20th	Day	28% 7% 14% 31% 18% 2	4365
	21st to end	Day	35% 10% 19% 25% 10% 1	4339
August	1st to 10th	Day	28% 7% 15% 36% 14% 1	4090
	11th to 20th	Day	38% 7% 13% 24% 17% 1	3831
	21st to end	Day	28% 7% 15% 32% 14% 3	4179
September	1st to 10th	Day	33% 6% 11% 24% 21% 5%	2280
	11th to 20th	Day	31% 5% 11% 27% 23% 4	2280
	21st to end	Day	30% 6% 10% 27% 24% 3	2036
October	1st to 10th	Day	18% 3 6% 19% 46% 8%	3160
	11th to 20th	Day	24% 3 6% 20% 38% 8%	3140
	21st to end	Day	34% 4 8% 26% 26% 2	3428
November	1st to 10th	Day	31% 4 13% 25% 21% 5%	1720
	11th to 20th	Day	38% 4 10% 24% 20% 4	1710
	21st to end	Day	45% 4 10% 26% 14%	1578
December	1st to 10th	Day	44% 5% 13% 25% 12% 1	1520
	11th to 20th	Day	44% 6% 12% 23% 13% 2	1915
	21st to end	Day	60% 7% 9% 15% 8% 1	2783
January	1st to 10th	Night	52% 6% 10% 23% 9% 1	4428
	11th to 20th	Night	57% 5% 9% 19% 9% 1	4170
	21st to end	Night	60% 4 9% 20% 6% 1	4532
February	1st to 10th	Night	51% 6% 10% 19% 12% 2	2470
	11th to 20th	Night	45% 5% 10% 22% 16% 3	2286
	21st to end	Night	46% 4 11% 21% 15% 3	1884
March	1st to 10th	Night	46% 5% 8% 23% 16% 2	3619
	11th to 20th	Night	35% 5% 11% 23% 22% 4	3480
	21st to end	Night	52% 9% 10% 23% 6%	3666
April	1st to 10th	Night	37% 7% 11% 25% 17% 4	1900
	11th to 20th	Night	39% 6% 10% 22% 19% 5%	1875
	21st to end	Night	44% 5% 10% 22% 17% 1	1900
May	1st to 10th	Night	40% 10% 16% 18% 14% 1	3059
	11th to 20th	Night	40% 10% 12% 26% 11% 1	2507
	21st to end	Night	31% 11% 15% 22% 20% 2	2751
June	1st to 10th	Night	28% 8% 16% 27% 18% 3	1520
	11th to 20th	Night	28% 7% 11% 26% 25% 4	1520
	21st to end	Night	25% 8% 15% 27% 18% 7%	1520
July	1st to 10th	Night	36% 6% 11% 31% 13% 2	2490
	11th to 20th	Night	20% 5% 14% 37% 22% 2	2482
	21st to end	Night	34% 7% 20% 26% 12% 1	2968
August	1st to 10th	Night	23% 6% 17% 34% 19% 1	2826
	11th to 20th	Night	35% 5% 12% 27% 19% 2	3066
	21st to end	Night	23% 6% 19% 32% 17% 3	3476
September	1st to 10th	Night	29% 6% 10% 24% 25% 6%	1900
	11th to 20th	Night	30% 7% 10% 24% 25% 4	1900
	21st to end	Night	29% 6% 9% 25% 27% 4	2122
October	1st to 10th	Night	17% 4 7% 19% 47% 7%	3800
	11th to 20th	Night	23% 2 7% 23% 34% 11%	3779
	21st to end	Night	32% 4 8% 26% 26% 4	4120
November	1st to 10th	Night	30% 6% 12% 25% 21% 6%	2428
	11th to 20th	Night	36% 4 8% 27% 21% 4	2470
	21st to end	Night	43% 5% 11% 24% 16% 2	2598
December	1st to 10th	Night	48% 6% 10% 23% 11% 1	2660
	11th to 20th	Night	46% 4 10% 23% 16% 1	3281
	21st to end	Night	64% 6% 9% 12% 7% 1	4884

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	21% 24% 34% 17% 4	270
	11th to 20th	Day	31% 21% 33% 14%	270
	21st to end	Day	18% 22% 43% 15% 3	297
February	1st to 10th	Day	24% 24% 36% 14% 2	270
	11th to 20th	Day	26% 23% 31% 17% 3 1	270
	21st to end	Day	29% 20% 37% 12% 2	225
March	1st to 10th	Day	21% 23% 42% 13% 1	270
	11th to 20th	Day	30% 21% 31% 15% 2 1	270
	21st to end	Day	33% 19% 31% 14% 3	382
April	1st to 10th	Day	20% 14% 40% 19% 6%	460
	11th to 20th	Day	24% 18% 30% 20% 8% 1	452
	21st to end	Day	26% 14% 35% 20% 5% 1	460
May	1st to 10th	Day	18% 16% 34% 25% 6% 1	501
	11th to 20th	Day	18% 12% 28% 27% 13% 2	675
	21st to end	Day	13% 11% 29% 28% 13% 6%	734
June	1st to 10th	Day	9% 5% 24% 33% 23% 7%	680
	11th to 20th	Day	9% 5% 22% 38% 23% 4	680
	21st to end	Day	5% 7% 32% 37% 15% 4	680
July	1st to 10th	Day	11% 2 17% 29% 30% 11%	671
	11th to 20th	Day	5% 4 24% 36% 26% 6%	668
	21st to end	Day	9% 4 18% 33% 30% 7%	739
August	1st to 10th	Day	8% 3 18% 38% 25% 7%	676
	11th to 20th	Day	10% 4 20% 34% 25% 7%	520
	21st to end	Day	9% 2 17% 33% 30% 9%	539
September	1st to 10th	Day	12% 4 17% 34% 25% 9%	490
	11th to 20th	Day	9% 3 17% 33% 28% 10%	490
	21st to end	Day	9% 10% 24% 28% 22% 8%	426
October	1st to 10th	Day	10% 13% 27% 30% 16% 5%	300
	11th to 20th	Day	20% 19% 29% 24% 7%	300
	21st to end	Day	28% 20% 32% 18% 3	330
November	1st to 10th	Day	14% 14% 35% 24% 10% 3	279
	11th to 20th	Day	21% 19% 33% 17% 9% 2	270
	21st to end	Day	26% 15% 31% 23% 3 1	270
December	1st to 10th	Day	16% 20% 39% 15% 6% 4	270
	11th to 20th	Day	22% 17% 36% 20% 5%	270
	21st to end	Day	25% 25% 36% 12% 2	297
January	1st to 10th	Night	18% 17% 39% 20% 5%	950
	11th to 20th	Night	22% 18% 36% 19% 4 1	950
	21st to end	Night	19% 19% 38% 22% 2	1045
February	1st to 10th	Night	21% 16% 38% 23% 2	950
	11th to 20th	Night	21% 17% 38% 21% 2	810
	21st to end	Night	24% 19% 38% 18% 2	628
March	1st to 10th	Night	23% 16% 39% 20% 3	698
	11th to 20th	Night	21% 14% 35% 25% 5%	570
	21st to end	Night	25% 15% 35% 21% 4	627
April	1st to 10th	Night	16% 18% 38% 24% 5%	570
	11th to 20th	Night	17% 14% 34% 28% 7%	563
	21st to end	Night	21% 12% 39% 23% 5%	570
May	1st to 10th	Night	15% 11% 33% 32% 9% 1	570
	11th to 20th	Night	19% 7% 28% 32% 14% 1	561
	21st to end	Night	12% 4 28% 36% 18% 2	617
June	1st to 10th	Night	8% 3 22% 40% 26% 1	570
	11th to 20th	Night	8% 2 24% 45% 20% 1	570
	21st to end	Night	4 2 27% 46% 20% 1	570
July	1st to 10th	Night	11% 2 10% 41% 32% 5%	555
	11th to 20th	Night	5% 2 15% 44% 31% 2	552
	21st to end	Night	7% 2 16% 40% 34% 2	624
August	1st to 10th	Night	7% 1 14% 44% 32% 2	567
	11th to 20th	Night	8% 1 16% 41% 30% 4	564
	21st to end	Night	6% 1 15% 39% 36% 3	627
September	1st to 10th	Night	13% 2 17% 37% 26% 5%	570
	11th to 20th	Night	10% 4 16% 34% 32% 4	570
	21st to end	Night	9% 7% 23% 33% 23% 4	731
October	1st to 10th	Night	9% 6% 28% 33% 21% 4	760
	11th to 20th	Night	15% 13% 32% 29% 11% 1	760
	21st to end	Night	21% 13% 34% 25% 6%	836
November	1st to 10th	Night	12% 10% 39% 29% 10%	755
	11th to 20th	Night	17% 16% 34% 26% 7%	760
	21st to end	Night	22% 14% 35% 23% 6%	888
December	1st to 10th	Night	21% 15% 36% 22% 5% 1	950
	11th to 20th	Night	23% 13% 32% 28% 4	950
	21st to end	Night	25% 20% 34% 19% 2	1045

Page generated at 2024-11-01 21:47:42. Version ac07

Copyright © 2024 Attilla Danko.