Monkton Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monkton Observing Site clear sky chart from 2005-11-06 to 2024-10-25.

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	14% 11% 4 9% 5% 5% 5% 4 6% 7% 30%	101612
	Night	14% 12% 5% 10% 6% 5% 4 3 5% 6% 30%	97171
Transparency	Day	54% 3 11% 21% 10% 1	101373
	Night	56% 3 10% 20% 10% 1	97031
Seeing	Day	19% 10% 28% 25% 13% 5%	15012
	Night	20% 10% 29% 29% 11% 1	24144

By Month

Percentage Cloud Cover NE (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	15% 19% 10% 15% 6% 4 3 2 3 4 17%	2319
	11th to 20th	Day	11% 19% 10% 23% 7% 8% 7% 2 3 3 6%	2840
	21st to end	Day	19% 22% 8% 17% 7% 5% 4 3 4 3 8%	3124
February	1st to 10th	Day	14% 18% 7% 17% 10% 7% 4 3 4 5% 13%	1710
	11th to 20th	Day	12% 14% 8% 15% 9% 6% 6% 4 5% 6% 16%	1663
	21st to end	Day	14% 17% 6% 13% 7% 6% 4 3 5% 5% 21%	1543
March	1st to 10th	Day	17% 15% 6% 11% 6% 5% 4 3 3 5% 26%	3360
	11th to 20th	Day	10% 16% 7% 11% 5% 5% 5% 4 4 6% 26%	3480
	21st to end	Day	15% 12% 4 11% 6% 5% 5% 3 4 5% 28%	3815
April	1st to 10th	Day	16% 16% 5% 8% 4 4 4 4 6% 6% 26%	2175
	11th to 20th	Day	18% 11% 3 6% 4 4 4 3 5% 7% 34%	2422
	21st to end	Day	20% 11% 4 7% 4 4 4 3 5% 7% 31%	2470
May	1st to 10th	Day	17% 9% 3 7% 4 5% 5% 4 5% 8% 33%	4108
	11th to 20th	Day	17% 9% 3 8% 5% 4 5% 4 6% 8% 31%	4171
	21st to end	Day	14% 5% 2 5% 4 4 4 4 5% 8% 45%	4837
June	1st to 10th	Day	14% 7% 3 6% 6% 5% 4 4 6% 8% 36%	2674
	11th to 20th	Day	11% 6% 3 6% 4 5% 5% 5% 7% 9% 40%	2850
	21st to end	Day	14% 8% 2 6% 5% 5% 5% 4 7% 8% 38%	2850
July	1st to 10th	Day	11% 5% 3 6% 5% 4 5% 5% 8% 9% 39%	4760
	11th to 20th	Day	11% 5% 2 5% 4 5% 5% 5% 7% 8% 42%	4363
	21st to end	Day	9% 6% 2 6% 4 4 6% 5% 7% 10% 41%	4466
August	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 5% 7% 9% 36%	4104
	11th to 20th	Day	11% 8% 3 7% 5% 5% 6% 5% 8% 10% 33%	4044
	21st to end	Day	9% 6% 2 7% 4 5% 6% 5% 7% 9% 40%	4472
September	1st to 10th	Day	12% 6% 3 8% 5% 5% 4 4 5% 10% 38%	2251
	11th to 20th	Day	11% 6% 2 5% 4 5% 5% 4 7% 7% 43%	2090
	21st to end	Day	16% 8% 2 7% 5% 4 5% 4 7% 7% 33%	2090
October	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 3 6% 5% 34%	1928
	11th to 20th	Day	21% 11% 4 8% 6% 4 5% 4 5% 7% 25%	1900
	21st to end	Day	24% 15% 4 9% 5% 5% 5% 3 6% 6% 18%	1991
November	1st to 10th	Day	14% 16% 4 9% 6% 4 4 3 6% 6% 28%	1668
	11th to 20th	Day	14% 16% 5% 9% 6% 5% 6% 4 6% 6% 21%	1520
	21st to end	Day	17% 19% 9% 11% 6% 5% 4 3 6% 6% 14%	1520
December	1st to 10th	Day	14% 23% 10% 15% 6% 5% 4 4 5% 4 10%	1520
	11th to 20th	Day	18% 19% 7% 16% 6% 4 4 3 5% 4 13%	1906
	21st to end	Day	27% 22% 8% 13% 5% 4 4 3 3 4 7%	2608
January	1st to 10th	Night	15% 20% 8% 20% 7% 6% 4 3 4 4 10%	4610
	11th to 20th	Night	13% 15% 9% 19% 10% 8% 6% 5% 5% 3 7%	4120
	21st to end	Night	19% 17% 9% 16% 7% 5% 4 3 4 4 12%	4532
February	1st to 10th	Night	15% 19% 6% 13% 10% 6% 4 3 4 4 15%	2470
	11th to 20th	Night	13% 15% 6% 13% 8% 6% 5% 4 6% 6% 18%	2403
	21st to end	Night	16% 13% 6% 13% 7% 4 5% 4 5% 5% 22%	1908
March	1st to 10th	Night	14% 11% 5% 9% 5% 4 4 3 5% 6% 32%	3479
	11th to 20th	Night	10% 11% 5% 11% 6% 5% 4 3 6% 7% 32%	3479
	21st to end	Night	14% 11% 4 9% 5% 5% 4 3 4 5% 37%	3817
April	1st to 10th	Night	19% 12% 4 7% 5% 4 4 3 5% 5% 31%	2005
	11th to 20th	Night	17% 11% 3 6% 5% 4 4 3 5% 7% 35%	1723
	21st to end	Night	16% 11% 4 8% 5% 4 4 3 5% 6% 34%	1710
May	1st to 10th	Night	16% 8% 3 6% 4 4 4 3 5% 7% 41%	2833
	11th to 20th	Night	14% 9% 3 8% 6% 5% 4 4 6% 6% 36%	2721
	21st to end	Night	10% 4 2 5% 3 4 4 4 6% 9% 49%	2738
June	1st to 10th	Night	13% 6% 2 7% 5% 4 5% 4 6% 8% 42%	1500
	11th to 20th	Night	9% 7% 2 5% 5% 5% 5% 4 6% 10% 42%	1330
	21st to end	Night	11% 6% 2 5% 4 6% 4 3 5% 8% 45%	1330
July	1st to 10th	Night	6% 5% 2 5% 4 4 5% 4 6% 9% 50%	2210
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 4 8% 53%	2580
	21st to end	Night	6% 5% 2 6% 5% 5% 6% 4 6% 7% 48%	3087
August	1st to 10th	Night	11% 6% 2 7% 4 4 4 4 5% 7% 45%	2825
	11th to 20th	Night	12% 9% 3 6% 4 4 4 3 6% 8% 42%	2785
	21st to end	Night	10% 6% 2 6% 4 4 5% 3 5% 7% 47%	3151
September	1st to 10th	Night	11% 6% 2 7% 5% 4 4 4 6% 7% 45%	1927
	11th to 20th	Night	10% 5% 2 5% 4 3 3 4 4 7% 53%	2090
	21st to end	Night	16% 8% 2 7% 5% 4 4 4 6% 7% 39%	2090
October	1st to 10th	Night	14% 8% 3 7% 5% 5% 5% 4 5% 7% 38%	2251
	11th to 20th	Night	20% 11% 4 7% 6% 4 5% 3 5% 6% 30%	2280
	21st to end	Night	22% 12% 3 10% 6% 4 4 4 6% 5% 24%	2467
November	1st to 10th	Night	14% 12% 4 8% 6% 4 5% 3 5% 7% 32%	2408
	11th to 20th	Night	14% 16% 5% 11% 6% 5% 4 4 6% 7% 22%	2660
	21st to end	Night	19% 16% 6% 11% 7% 5% 4 3 5% 6% 18%	2660
December	1st to 10th	Night	17% 23% 8% 13% 6% 4 4 3 4 4 12%	2660
	11th to 20th	Night	14% 21% 7% 15% 7% 5% 4 4 4 5% 14%	3288
	21st to end	Night	25% 23% 9% 13% 5% 4 4 3 4 4 8%	5044

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	73% 2 9% 10% 6%	2320
	11th to 20th	Day	85% 2 4 6% 3	2840
	21st to end	Day	82% 2 6% 7% 3	3124
February	1st to 10th	Day	75% 3 6% 12% 3	1710
	11th to 20th	Day	68% 4 7% 14% 6% 1	1672
	21st to end	Day	66% 3 10% 14% 6% 1	1543
March	1st to 10th	Day	63% 2 10% 19% 6% 1	3363
	11th to 20th	Day	60% 2 11% 18% 7% 1	3480
	21st to end	Day	59% 2 10% 17% 11% 2	3815
April	1st to 10th	Day	57% 4 10% 19% 10%	2175
	11th to 20th	Day	51% 3 11% 21% 13% 1	2422
	21st to end	Day	54% 3 11% 19% 11% 2	2470
May	1st to 10th	Day	51% 2 10% 22% 13% 2	4120
	11th to 20th	Day	52% 2 13% 24% 7% 1	4175
	21st to end	Day	39% 2 12% 22% 19% 5%	4837
June	1st to 10th	Day	45% 4 12% 25% 14% 1	2674
	11th to 20th	Day	41% 4 12% 26% 16% 1	2850
	21st to end	Day	44% 4 12% 26% 14%	2850
July	1st to 10th	Day	41% 2 15% 25% 16% 2	4686
	11th to 20th	Day	38% 2 10% 36% 12% 1	4285
	21st to end	Day	39% 3 14% 25% 18% 2	4324
August	1st to 10th	Day	45% 3 12% 26% 13% 1	4091
	11th to 20th	Day	46% 3 16% 27% 9%	4083
	21st to end	Day	40% 3 13% 33% 12% 1	4472
September	1st to 10th	Day	42% 5% 13% 27% 11% 2	2251
	11th to 20th	Day	39% 4 12% 30% 15% 1	2090
	21st to end	Day	49% 4 13% 25% 9% 1	2090
October	1st to 10th	Day	51% 3 11% 20% 13% 1	1928
	11th to 20th	Day	58% 3 11% 18% 8%	1900
	21st to end	Day	66% 3 11% 14% 6%	1991
November	1st to 10th	Day	57% 4 10% 21% 8% 1	1668
	11th to 20th	Day	61% 4 12% 15% 7% 1	1520
	21st to end	Day	70% 4 11% 12% 4	1520
December	1st to 10th	Day	76% 5% 7% 10% 2	1520
	11th to 20th	Day	75% 3 9% 10% 3	1906
	21st to end	Day	83% 2 8% 6% 1	2608
January	1st to 10th	Night	79% 2 6% 9% 3	4610
	11th to 20th	Night	81% 2 8% 7% 2	4120
	21st to end	Night	78% 2 7% 9% 4 1	4532
February	1st to 10th	Night	72% 4 6% 14% 3	2470
	11th to 20th	Night	65% 3 9% 14% 7%	2405
	21st to end	Night	63% 3 11% 15% 8%	1908
March	1st to 10th	Night	54% 2 12% 24% 7% 1	3489
	11th to 20th	Night	52% 2 12% 21% 11% 1	3480
	21st to end	Night	52% 2 8% 22% 14% 2	3817
April	1st to 10th	Night	55% 3 8% 19% 14% 1	2005
	11th to 20th	Night	50% 4 8% 20% 16% 2	1723
	21st to end	Night	52% 2 8% 19% 15% 3	1710
May	1st to 10th	Night	45% 2 11% 21% 16% 5%	2840
	11th to 20th	Night	50% 2 12% 23% 11% 2	2722
	21st to end	Night	33% 2 14% 25% 22% 4	2739
June	1st to 10th	Night	40% 4 9% 28% 17% 2	1500
	11th to 20th	Night	37% 4 13% 27% 17% 3	1330
	21st to end	Night	38% 4 13% 27% 17% 1	1330
July	1st to 10th	Night	32% 3 14% 27% 20% 6%	2175
	11th to 20th	Night	32% 3 12% 33% 19% 1	2536
	21st to end	Night	36% 4 13% 27% 19% 2	2988
August	1st to 10th	Night	40% 3 12% 28% 16% 1	2814
	11th to 20th	Night	41% 3 15% 27% 13% 1	2812
	21st to end	Night	37% 3 10% 34% 15% 1	3151
September	1st to 10th	Night	39% 4 11% 29% 15% 2	1927
	11th to 20th	Night	32% 4 11% 31% 21% 1	2090
	21st to end	Night	45% 4 14% 26% 12%	2090
October	1st to 10th	Night	47% 4 9% 23% 16% 1	2251
	11th to 20th	Night	55% 3 10% 22% 9%	2280
	21st to end	Night	60% 4 9% 17% 9%	2467
November	1st to 10th	Night	52% 4 11% 23% 10% 1	2408
	11th to 20th	Night	62% 3 11% 17% 6% 1	2660
	21st to end	Night	66% 4 13% 12% 4	2660
December	1st to 10th	Night	76% 4 8% 10% 3	2660
	11th to 20th	Night	72% 3 11% 11% 2	3288
	21st to end	Night	82% 2 8% 6% 1	5044

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% 18% 34% 18% 8% 1	211
	11th to 20th	Day	21% 14% 46% 13% 4 1	270
	21st to end	Day	27% 12% 32% 24% 3 1	297
February	1st to 10th	Day	21% 17% 42% 14% 5%	270
	11th to 20th	Day	21% 20% 39% 17% 2	270
	21st to end	Day	27% 26% 30% 16% 1	225
March	1st to 10th	Day	25% 11% 38% 18% 7% 1	410
	11th to 20th	Day	21% 13% 34% 23% 8% 1	460
	21st to end	Day	27% 10% 33% 24% 5% 1	506
April	1st to 10th	Day	22% 15% 33% 22% 7% 1	460
	11th to 20th	Day	26% 14% 29% 17% 10% 5%	452
	21st to end	Day	26% 10% 31% 23% 8% 2	460
May	1st to 10th	Day	24% 9% 26% 26% 11% 4	463
	11th to 20th	Day	21% 7% 26% 22% 18% 5%	487
	21st to end	Day	16% 5% 27% 26% 19% 7%	529
June	1st to 10th	Day	16% 10% 27% 30% 14% 3	504
	11th to 20th	Day	14% 8% 27% 32% 15% 3	680
	21st to end	Day	16% 8% 27% 34% 11% 5%	680
July	1st to 10th	Day	11% 5% 22% 31% 22% 10%	671
	11th to 20th	Day	16% 4 24% 28% 20% 9%	557
	21st to end	Day	12% 2 23% 34% 21% 8%	532
August	1st to 10th	Day	12% 4 20% 27% 25% 13%	486
	11th to 20th	Day	14% 3 17% 29% 21% 16%	479
	21st to end	Day	17% 5% 18% 29% 20% 11%	539
September	1st to 10th	Day	14% 6% 20% 28% 19% 13%	490
	11th to 20th	Day	9% 5% 18% 28% 27% 14%	490
	21st to end	Day	16% 10% 24% 27% 15% 9%	490
October	1st to 10th	Day	22% 8% 26% 22% 16% 6%	490
	11th to 20th	Day	22% 13% 31% 25% 7% 1	490
	21st to end	Day	31% 12% 31% 20% 6% 1	478
November	1st to 10th	Day	24% 18% 30% 18% 9% 1	268
	11th to 20th	Day	24% 17% 32% 18% 6% 2	180
	21st to end	Day	23% 18% 38% 18% 3	180
December	1st to 10th	Day	26% 23% 29% 17% 4	180
	11th to 20th	Day	30% 22% 31% 16% 2	180
	21st to end	Day	33% 18% 36% 12% 2	198
January	1st to 10th	Night	23% 16% 35% 20% 6% 1	935
	11th to 20th	Night	27% 15% 32% 21% 4	760
	21st to end	Night	20% 12% 37% 24% 6%	836
February	1st to 10th	Night	25% 15% 36% 22% 2	760
	11th to 20th	Night	21% 14% 36% 23% 6%	743
	21st to end	Night	24% 15% 36% 22% 4	628
March	1st to 10th	Night	20% 12% 37% 24% 7%	760
	11th to 20th	Night	18% 15% 38% 21% 6%	760
	21st to end	Night	22% 10% 33% 25% 9% 1	836
April	1st to 10th	Night	24% 12% 32% 27% 4	760
	11th to 20th	Night	24% 10% 32% 23% 10% 1	599
	21st to end	Night	21% 9% 31% 33% 7%	570
May	1st to 10th	Night	19% 6% 31% 30% 14% 1	570
	11th to 20th	Night	20% 5% 25% 35% 14% 1	509
	21st to end	Night	13% 3 28% 39% 18%	411
June	1st to 10th	Night	14% 3 28% 39% 14% 1	380
	11th to 20th	Night	12% 6% 28% 41% 14%	380
	21st to end	Night	15% 3 26% 40% 14% 1	380
July	1st to 10th	Night	7% 1 19% 48% 24% 1	370
	11th to 20th	Night	10% 2 21% 42% 24% 2	478
	21st to end	Night	10% 1 18% 48% 22% 1	624
August	1st to 10th	Night	11% 2 13% 45% 27% 3	567
	11th to 20th	Night	9% 2 16% 40% 28% 5%	564
	21st to end	Night	15% 2 19% 34% 26% 3	641
September	1st to 10th	Night	13% 4 23% 34% 21% 5%	760
	11th to 20th	Night	12% 3 18% 35% 26% 5%	760
	21st to end	Night	19% 6% 20% 34% 17% 5%	760
October	1st to 10th	Night	19% 5% 28% 29% 16% 2	760
	11th to 20th	Night	25% 10% 27% 28% 10% 1	760
	21st to end	Night	29% 10% 32% 25% 5%	812
November	1st to 10th	Night	22% 10% 28% 30% 9% 1	740
	11th to 20th	Night	22% 14% 34% 21% 7% 1	760
	21st to end	Night	26% 12% 33% 24% 5%	760
December	1st to 10th	Night	27% 18% 30% 19% 5%	760
	11th to 20th	Night	23% 18% 36% 18% 4 1	760
	21st to end	Night	29% 14% 35% 19% 2	931

Page generated at 2024-10-22 20:21:05. Version ac07

Copyright © 2024 Attilla Danko.