Mikes Mobile Notary Service, Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mikes Mobile Notary Service, Observatory clear sky chart from 2005-11-06 to 2026-03-18.

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% 6% 2 6% 4 4 4 3 5% 7% 47%	131543
	Night	14% 6% 2 5% 3 3 3 3 5% 7% 50%	130290
Transparency	Day	35% 5% 10% 21% 19% 9%	135286
	Night	34% 4 10% 20% 20% 12%	134611
Seeing	Day	14% 5% 20% 28% 25% 9%	16610
	Night	15% 6% 25% 36% 16% 2	26646

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	14% 9% 2 5% 3 3 3 3 4 6% 49%	5289
	11th to 20th	Day	14% 4 2 5% 3 2 3 3 5% 5% 55%	5310
	21st to end	Day	25% 8% 3 7% 3 3 2 2 3 5% 39%	6010
February	1st to 10th	Day	20% 8% 2 5% 3 4 3 3 3 5% 45%	2100
	11th to 20th	Day	19% 7% 3 5% 3 3 4 2 4 6% 44%	2049
	21st to end	Day	18% 7% 2 5% 3 3 3 2 3 5% 49%	1750
March	1st to 10th	Day	13% 6% 2 6% 4 4 3 3 5% 6% 48%	5046
	11th to 20th	Day	14% 6% 2 6% 4 3 4 2 4 6% 49%	5057
	21st to end	Day	16% 8% 3 6% 4 4 3 3 4 6% 44%	5462
April	1st to 10th	Day	15% 9% 3 6% 4 4 4 3 5% 7% 41%	2200
	11th to 20th	Day	15% 8% 3 8% 4 4 3 3 5% 5% 42%	2191
	21st to end	Day	14% 6% 2 6% 5% 4 3 3 5% 7% 44%	2518
May	1st to 10th	Day	19% 8% 3 7% 4 4 4 4 6% 7% 34%	5862
	11th to 20th	Day	11% 5% 2 7% 4 5% 4 4 5% 8% 44%	5862
	21st to end	Day	12% 7% 2 7% 5% 5% 6% 5% 8% 9% 34%	6434
June	1st to 10th	Day	6% 4 2 6% 4 4 6% 4 7% 9% 49%	2600
	11th to 20th	Day	7% 4 2 5% 4 4 5% 5% 7% 9% 49%	2600
	21st to end	Day	5% 5% 2 7% 5% 6% 7% 5% 7% 9% 41%	2600
July	1st to 10th	Day	9% 6% 2 7% 5% 4 5% 5% 7% 10% 40%	5900
	11th to 20th	Day	5% 4 2 5% 4 5% 5% 4 7% 13% 46%	5900
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 11% 42%	6422
August	1st to 10th	Day	1 1 1 2 2 3 3 3 5% 8% 72%	4234
	11th to 20th	Day	4 2 1 3 3 3 4 4 7% 13% 57%	4015
	21st to end	Day	4 3 1 5% 5% 5% 5% 5% 8% 11% 49%	4055
September	1st to 10th	Day	7% 6% 2 7% 5% 5% 5% 4 6% 7% 46%	2200
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 4 7% 8% 44%	2200
	21st to end	Day	6% 4 2 4 4 5% 6% 5% 7% 7% 51%	2200
October	1st to 10th	Day	6% 3 2 4 3 3 4 3 5% 6% 61%	2200
	11th to 20th	Day	12% 5% 2 4 2 3 3 2 4 5% 56%	2010
	21st to end	Day	11% 4 1 5% 3 3 3 2 4 5% 59%	2200
November	1st to 10th	Day	13% 7% 2 6% 3 4 3 3 5% 6% 48%	2058
	11th to 20th	Day	11% 6% 2 5% 4 4 3 3 5% 5% 53%	2021
	21st to end	Day	16% 7% 2 6% 4 4 3 3 5% 6% 45%	1890
December	1st to 10th	Day	23% 7% 3 6% 3 3 3 3 3 5% 41%	3030
	11th to 20th	Day	19% 7% 2 6% 4 3 4 3 4 5% 43%	3481
	21st to end	Day	14% 6% 2 4 3 3 3 2 4 4 55%	4587
January	1st to 10th	Night	15% 7% 2 5% 3 3 3 2 3 5% 53%	7634
	11th to 20th	Night	10% 4 1 3 2 2 3 3 4 5% 63%	7680
	21st to end	Night	29% 6% 2 6% 3 3 3 2 3 5% 39%	8248
February	1st to 10th	Night	18% 7% 2 5% 3 3 3 2 3 5% 49%	2520
	11th to 20th	Night	20% 6% 2 5% 2 3 3 2 3 5% 47%	2458
	21st to end	Night	19% 8% 2 4 3 3 3 3 4 5% 47%	2055
March	1st to 10th	Night	17% 7% 2 5% 4 4 4 3 5% 6% 44%	5029
	11th to 20th	Night	15% 7% 2 6% 3 3 4 3 4 5% 49%	5057
	21st to end	Night	17% 10% 2 6% 3 3 3 3 4 5% 43%	5467
April	1st to 10th	Night	14% 6% 2 5% 4 4 4 4 5% 6% 46%	2200
	11th to 20th	Night	16% 6% 2 5% 4 3 4 3 5% 6% 45%	2155
	21st to end	Night	16% 6% 2 5% 4 3 3 2 5% 6% 48%	1876
May	1st to 10th	Night	22% 7% 2 7% 4 4 4 3 5% 6% 34%	4053
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 5% 8% 47%	4053
	21st to end	Night	12% 7% 3 7% 4 4 5% 4 6% 9% 39%	4443
June	1st to 10th	Night	4 3 1 3 3 3 3 3 7% 10% 60%	1800
	11th to 20th	Night	5% 3 1 4 4 3 4 4 6% 9% 57%	1800
	21st to end	Night	5% 4 1 4 4 4 6% 4 7% 10% 53%	1800
July	1st to 10th	Night	9% 6% 2 6% 4 4 5% 5% 7% 10% 43%	4078
	11th to 20th	Night	5% 3 1 4 3 3 4 4 7% 11% 53%	4077
	21st to end	Night	7% 4 2 5% 4 4 5% 4 6% 11% 47%	4449
August	1st to 10th	Night	1 1 1 1 2 2 3 5% 8% 75%	2926
	11th to 20th	Night	3 2 1 3 3 3 4 4 7% 11% 59%	3039
	21st to end	Night	3 2 1 4 3 3 4 4 7% 11% 57%	3843
September	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 6% 8% 52%	2200
	11th to 20th	Night	9% 5% 2 6% 4 5% 4 4 5% 7% 48%	2200
	21st to end	Night	7% 4 1 4 3 5% 4 3 6% 8% 55%	2200
October	1st to 10th	Night	5% 3 1 3 3 4 4 3 4 6% 65%	2200
	11th to 20th	Night	11% 4 2 4 3 3 3 3 4 6% 58%	2367
	21st to end	Night	14% 3 1 4 2 2 3 2 4 4 61%	2640
November	1st to 10th	Night	13% 6% 2 4 3 3 3 3 3 6% 55%	2460
	11th to 20th	Night	11% 6% 2 5% 4 3 3 3 4 5% 56%	2594
	21st to end	Night	18% 5% 2 5% 3 3 4 3 3 6% 48%	2730
December	1st to 10th	Night	23% 8% 2 6% 3 3 4 2 4 5% 41%	4380
	11th to 20th	Night	20% 9% 2 5% 3 2 2 2 3 5% 47%	4946
	21st to end	Night	17% 6% 2 4 3 2 2 2 2 4 56%	6633

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	39% 4 6% 24% 21% 8%	5290
	11th to 20th	Day	33% 2 4 18% 26% 17%	5310
	21st to end	Day	51% 2 4 10% 23% 11%	6010
February	1st to 10th	Day	44% 4 5% 12% 21% 14%	2100
	11th to 20th	Day	44% 3 7% 18% 19% 10%	2059
	21st to end	Day	40% 2 5% 20% 19% 14%	1750
March	1st to 10th	Day	37% 4 5% 19% 17% 18%	5046
	11th to 20th	Day	38% 3 6% 9% 17% 27%	5057
	21st to end	Day	42% 4 8% 19% 20% 7%	5464
April	1st to 10th	Day	44% 4 8% 17% 15% 13%	2200
	11th to 20th	Day	44% 3 7% 16% 19% 11%	2191
	21st to end	Day	40% 5% 6% 21% 20% 8%	2518
May	1st to 10th	Day	47% 5% 10% 20% 14% 4	5900
	11th to 20th	Day	37% 5% 12% 19% 22% 6%	5866
	21st to end	Day	41% 7% 10% 26% 13% 2	6447
June	1st to 10th	Day	29% 5% 15% 28% 20% 4	2600
	11th to 20th	Day	30% 5% 12% 29% 19% 5%	2600
	21st to end	Day	35% 8% 13% 25% 16% 2	2600
July	1st to 10th	Day	37% 7% 21% 29% 5% 1	5836
	11th to 20th	Day	28% 8% 20% 30% 13% 1	5831
	21st to end	Day	33% 8% 18% 25% 13% 3	6240
August	1st to 10th	Day	12% 4 12% 41% 29% 1	4220
	11th to 20th	Day	19% 5% 23% 39% 11% 2	4054
	21st to end	Day	26% 11% 20% 24% 18% 2	4054
September	1st to 10th	Day	37% 5% 10% 22% 17% 9%	2200
	11th to 20th	Day	36% 6% 13% 21% 19% 5%	2200
	21st to end	Day	29% 6% 9% 23% 18% 15%	2200
October	1st to 10th	Day	15% 3 6% 15% 23% 38%	3590
	11th to 20th	Day	20% 3 7% 20% 33% 18%	3250
	21st to end	Day	25% 4 5% 21% 31% 15%	3538
November	1st to 10th	Day	37% 4 8% 18% 22% 11%	2058
	11th to 20th	Day	34% 3 8% 19% 21% 15%	2021
	21st to end	Day	42% 2 7% 17% 19% 12%	1890
December	1st to 10th	Day	48% 3 6% 16% 18% 9%	3030
	11th to 20th	Day	42% 5% 7% 11% 23% 13%	3479
	21st to end	Day	35% 3 4 17% 27% 14%	4587
January	1st to 10th	Night	37% 3 5% 20% 23% 13%	7635
	11th to 20th	Night	26% 2 4 17% 31% 19%	7680
	21st to end	Night	50% 3 3 12% 21% 12%	8248
February	1st to 10th	Night	40% 3 6% 14% 21% 17%	2520
	11th to 20th	Night	41% 3 6% 17% 19% 13%	2458
	21st to end	Night	41% 3 5% 16% 19% 15%	2055
March	1st to 10th	Night	41% 4 6% 16% 20% 14%	5029
	11th to 20th	Night	39% 3 8% 11% 14% 24%	5057
	21st to end	Night	44% 4 8% 16% 18% 10%	5467
April	1st to 10th	Night	39% 4 8% 18% 17% 14%	2200
	11th to 20th	Night	39% 3 10% 16% 16% 15%	2155
	21st to end	Night	39% 3 9% 21% 18% 9%	1876
May	1st to 10th	Night	49% 5% 8% 21% 12% 5%	4080
	11th to 20th	Night	34% 6% 12% 21% 20% 7%	4054
	21st to end	Night	40% 6% 14% 27% 11% 2	4452
June	1st to 10th	Night	20% 5% 19% 31% 22% 3	1800
	11th to 20th	Night	22% 6% 15% 32% 20% 5%	1800
	21st to end	Night	26% 7% 18% 30% 17% 3	1800
July	1st to 10th	Night	35% 9% 25% 26% 4	4035
	11th to 20th	Night	23% 7% 24% 33% 12%	4026
	21st to end	Night	30% 8% 20% 26% 11% 4	4320
August	1st to 10th	Night	8% 4 15% 44% 27% 1	2916
	11th to 20th	Night	18% 6% 30% 32% 12% 2	3066
	21st to end	Night	20% 11% 23% 29% 15% 2	3843
September	1st to 10th	Night	30% 6% 16% 24% 17% 8%	2200
	11th to 20th	Night	34% 6% 14% 24% 15% 7%	2200
	21st to end	Night	28% 4 15% 23% 18% 14%	2200
October	1st to 10th	Night	15% 3 7% 17% 20% 39%	3590
	11th to 20th	Night	18% 3 8% 18% 32% 21%	3853
	21st to end	Night	22% 3 5% 22% 30% 17%	4252
November	1st to 10th	Night	32% 3 9% 19% 23% 14%	2460
	11th to 20th	Night	32% 3 7% 20% 22% 16%	2594
	21st to end	Night	39% 2 8% 19% 17% 15%	2730
December	1st to 10th	Night	48% 3 5% 16% 19% 9%	4380
	11th to 20th	Night	41% 3 7% 10% 23% 16%	4947
	21st to end	Night	34% 3 4 16% 29% 14%	6633

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	20% 13% 34% 24% 8% 1	330
	11th to 20th	Day	25% 11% 27% 27% 8% 2	330
	21st to end	Day	24% 11% 37% 20% 8% 1	363
February	1st to 10th	Day	27% 11% 28% 25% 8% 1	330
	11th to 20th	Day	28% 15% 33% 19% 5% 1	330
	21st to end	Day	26% 11% 41% 18% 4	273
March	1st to 10th	Day	20% 16% 33% 24% 6% 1	330
	11th to 20th	Day	18% 13% 40% 21% 6% 1	321
	21st to end	Day	19% 10% 41% 22% 6% 1	330
April	1st to 10th	Day	23% 14% 37% 20% 5% 1	300
	11th to 20th	Day	20% 12% 32% 25% 10% 1	309
	21st to end	Day	22% 8% 35% 24% 9% 2	618
May	1st to 10th	Day	19% 5% 36% 29% 10%	703
	11th to 20th	Day	20% 4 28% 31% 14% 3	725
	21st to end	Day	14% 4 24% 37% 17% 4	789
June	1st to 10th	Day	7% 1 12% 43% 30% 7%	730
	11th to 20th	Day	7% 2 12% 47% 26% 6%	730
	21st to end	Day	5% 2 10% 34% 36% 13%	730
July	1st to 10th	Day	9% 2 5% 34% 37% 14%	721
	11th to 20th	Day	4 2 4 29% 48% 13%	718
	21st to end	Day	5% 1 5% 27% 48% 15%	794
August	1st to 10th	Day	3 1 2 22% 54% 18%	726
	11th to 20th	Day	6% 1 1 26% 48% 18%	624
	21st to end	Day	6% 1 2 21% 36% 34%	430
September	1st to 10th	Day	7% 1 4 23% 39% 27%	330
	11th to 20th	Day	5% 1 4 22% 43% 25%	330
	21st to end	Day	9% 1 5% 25% 38% 22%	330
October	1st to 10th	Day	5% 1 10% 27% 41% 17%	330
	11th to 20th	Day	10% 2 22% 30% 25% 11%	330
	21st to end	Day	18% 8% 22% 24% 22% 6%	363
November	1st to 10th	Day	17% 5% 19% 32% 18% 8%	330
	11th to 20th	Day	17% 5% 26% 29% 21% 3	330
	21st to end	Day	17% 14% 34% 21% 12% 2	330
December	1st to 10th	Day	19% 6% 33% 26% 12% 5%	330
	11th to 20th	Day	24% 11% 26% 25% 12% 1	330
	21st to end	Day	19% 10% 34% 26% 9% 2	363
January	1st to 10th	Night	19% 9% 32% 32% 8%	1050
	11th to 20th	Night	20% 10% 30% 32% 8%	1050
	21st to end	Night	23% 10% 30% 32% 6%	1105
February	1st to 10th	Night	24% 10% 32% 27% 7%	840
	11th to 20th	Night	25% 11% 36% 26% 3	824
	21st to end	Night	24% 13% 39% 20% 3	671
March	1st to 10th	Night	22% 12% 37% 26% 3	630
	11th to 20th	Night	20% 9% 36% 29% 5%	621
	21st to end	Night	15% 10% 44% 27% 3	660
April	1st to 10th	Night	17% 8% 41% 31% 3	600
	11th to 20th	Night	19% 8% 39% 28% 5%	593
	21st to end	Night	17% 8% 41% 27% 8% 1	600
May	1st to 10th	Night	17% 7% 42% 28% 5% 1	600
	11th to 20th	Night	14% 4 33% 35% 12% 1	591
	21st to end	Night	13% 3 30% 39% 13% 1	650
June	1st to 10th	Night	6% 2 21% 45% 26% 1	600
	11th to 20th	Night	6% 2 26% 49% 16% 1	600
	21st to end	Night	5% 1 13% 47% 29% 5%	600
July	1st to 10th	Night	7% 2 7% 47% 33% 4	585
	11th to 20th	Night	5% 1 7% 52% 32% 3	582
	21st to end	Night	4 1 7% 47% 37% 3	657
August	1st to 10th	Night	1 5% 51% 39% 3	597
	11th to 20th	Night	6% 5% 49% 34% 6%	594
	21st to end	Night	5% 1 3 36% 47% 8%	660
September	1st to 10th	Night	8% 2 6% 41% 38% 6%	600
	11th to 20th	Night	11% 1 4 39% 40% 5%	600
	21st to end	Night	9% 2 11% 39% 36% 4	600
October	1st to 10th	Night	5% 11% 49% 30% 5%	600
	11th to 20th	Night	12% 3 21% 40% 22% 2	767
	21st to end	Night	15% 6% 26% 32% 20% 1	880
November	1st to 10th	Night	14% 4 21% 39% 21% 1	820
	11th to 20th	Night	14% 5% 27% 39% 14% 1	914
	21st to end	Night	22% 7% 29% 28% 13% 1	1050
December	1st to 10th	Night	22% 6% 29% 31% 11% 1	1050
	11th to 20th	Night	25% 8% 26% 33% 7%	1050
	21st to end	Night	20% 7% 29% 35% 8%	1155

Page generated at 2026-03-15 01:23:57. Version ac07

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