Ogoki
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ogoki clear sky chart from 2005-11-06 to 2026-07-01.

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 10% 6% 6% 5% 4 5% 6% 28%	138914
	Night	12% 13% 5% 11% 7% 6% 6% 5% 5% 6% 24%	133725
Transparency	Day	56% 5% 11% 20% 8% 1	142275
	Night	60% 5% 10% 18% 7%	138451
Seeing	Day	20% 12% 31% 25% 10% 2	17854
	Night	20% 9% 31% 29% 10% 1	27066

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	6% 16% 7% 18% 10% 9% 6% 4 6% 6% 11%	4094
	11th to 20th	Day	5% 13% 6% 20% 10% 9% 11% 7% 8% 5% 7%	4363
	21st to end	Day	8% 11% 6% 13% 9% 10% 10% 7% 7% 6% 13%	5156
February	1st to 10th	Day	6% 12% 5% 10% 9% 7% 9% 9% 8% 7% 18%	1680
	11th to 20th	Day	6% 12% 6% 12% 7% 8% 9% 6% 7% 8% 19%	1787
	21st to end	Day	5% 12% 6% 12% 9% 8% 8% 6% 6% 6% 22%	1730
March	1st to 10th	Day	8% 14% 5% 16% 8% 7% 6% 3 4 5% 25%	4578
	11th to 20th	Day	11% 14% 4 14% 9% 8% 6% 3 5% 5% 21%	4854
	21st to end	Day	10% 16% 5% 12% 8% 10% 8% 4 5% 5% 19%	5949
April	1st to 10th	Day	10% 14% 4 11% 7% 6% 4 4 5% 6% 28%	2520
	11th to 20th	Day	17% 12% 3 8% 5% 5% 4 3 5% 5% 32%	2691
	21st to end	Day	16% 12% 4 8% 6% 4 5% 3 5% 5% 32%	2742
May	1st to 10th	Day	18% 16% 5% 10% 5% 4 3 3 3 4 31%	8241
	11th to 20th	Day	23% 13% 3 7% 4 4 4 3 4 5% 30%	8733
	21st to end	Day	19% 10% 2 5% 3 3 4 3 5% 7% 39%	9716
June	1st to 10th	Day	24% 9% 2 6% 5% 4 3 3 5% 7% 31%	3150
	11th to 20th	Day	15% 8% 3 7% 6% 5% 5% 4 5% 7% 35%	3158
	21st to end	Day	16% 7% 3 7% 6% 5% 5% 4 7% 7% 33%	3360
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 4 4 6% 8% 42%	6830
	11th to 20th	Day	18% 5% 2 6% 5% 5% 5% 4 6% 8% 37%	6820
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 6% 7% 9% 37%	7072
August	1st to 10th	Day	21% 6% 2 6% 4 4 5% 4 6% 7% 34%	4563
	11th to 20th	Day	11% 5% 2 5% 3 4 4 4 6% 9% 46%	4374
	21st to end	Day	14% 6% 3 7% 5% 5% 4 4 6% 8% 40%	4675
September	1st to 10th	Day	19% 9% 3 8% 4 4 4 4 5% 6% 33%	2407
	11th to 20th	Day	23% 10% 2 7% 6% 4 5% 3 5% 6% 29%	2240
	21st to end	Day	22% 13% 3 7% 5% 4 4 3 4 6% 31%	2200
October	1st to 10th	Day	21% 15% 4 8% 5% 5% 5% 3 5% 6% 22%	2111
	11th to 20th	Day	21% 20% 5% 8% 5% 5% 4 4 5% 5% 19%	1800
	21st to end	Day	20% 22% 5% 10% 6% 5% 5% 3 5% 4 17%	1980
November	1st to 10th	Day	20% 18% 6% 13% 5% 4 4 3 3 6% 16%	1796
	11th to 20th	Day	19% 21% 7% 15% 8% 5% 4 3 3 4 12%	1480
	21st to end	Day	18% 24% 8% 16% 8% 5% 3 3 2 3 10%	1470
December	1st to 10th	Day	7% 18% 10% 17% 11% 8% 5% 3 4 4 12%	2350
	11th to 20th	Day	9% 13% 7% 12% 7% 10% 8% 6% 7% 8% 14%	2691
	21st to end	Day	12% 17% 7% 13% 9% 9% 6% 5% 5% 4 13%	3553
January	1st to 10th	Night	5% 14% 6% 18% 11% 8% 9% 5% 5% 6% 12%	8831
	11th to 20th	Night	5% 15% 7% 18% 10% 9% 11% 8% 7% 4 6%	8535
	21st to end	Night	6% 11% 5% 11% 8% 10% 12% 7% 7% 6% 16%	9058
February	1st to 10th	Night	5% 11% 6% 12% 8% 9% 11% 7% 6% 6% 18%	2940
	11th to 20th	Night	6% 14% 6% 12% 8% 8% 9% 6% 8% 7% 17%	2719
	21st to end	Night	5% 11% 5% 12% 9% 7% 8% 7% 8% 7% 22%	2076
March	1st to 10th	Night	8% 10% 5% 13% 8% 6% 6% 4 6% 6% 27%	5482
	11th to 20th	Night	11% 15% 5% 15% 9% 6% 4 3 4 4 23%	5324
	21st to end	Night	11% 14% 4 10% 8% 7% 7% 4 5% 5% 23%	5267
April	1st to 10th	Night	14% 15% 4 9% 6% 6% 5% 4 4 4 30%	2100
	11th to 20th	Night	17% 11% 4 8% 5% 5% 4 4 6% 6% 31%	1878
	21st to end	Night	16% 11% 4 7% 5% 4 3 3 4 5% 37%	1874
May	1st to 10th	Night	14% 15% 4 10% 4 4 4 3 4 5% 35%	4688
	11th to 20th	Night	18% 13% 4 7% 5% 4 4 3 5% 6% 31%	4157
	21st to end	Night	20% 8% 2 5% 4 4 4 4 4 5% 39%	4492
June	1st to 10th	Night	22% 9% 3 8% 3 3 4 3 5% 6% 34%	1470
	11th to 20th	Night	16% 7% 2 5% 5% 4 4 4 7% 7% 38%	1450
	21st to end	Night	16% 6% 3 6% 5% 5% 5% 5% 6% 7% 37%	1260
July	1st to 10th	Night	12% 6% 2 7% 5% 5% 6% 4 7% 9% 38%	3116
	11th to 20th	Night	14% 6% 2 5% 5% 5% 6% 5% 7% 7% 37%	3160
	21st to end	Night	13% 6% 3 6% 4 4 4 4 7% 8% 42%	3800
August	1st to 10th	Night	20% 5% 2 4 3 4 5% 4 5% 8% 41%	2597
	11th to 20th	Night	9% 6% 2 6% 3 4 3 3 6% 8% 50%	2681
	21st to end	Night	11% 4 2 6% 5% 4 5% 4 6% 8% 44%	3223
September	1st to 10th	Night	19% 7% 1 6% 4 4 4 3 5% 7% 41%	1990
	11th to 20th	Night	21% 8% 3 7% 4 5% 4 3 6% 6% 34%	2140
	21st to end	Night	20% 9% 2 6% 4 4 4 3 5% 6% 37%	2200
October	1st to 10th	Night	23% 14% 3 6% 4 3 3 4 5% 7% 28%	2287
	11th to 20th	Night	21% 18% 5% 9% 5% 4 4 4 4 7% 19%	2600
	21st to end	Night	19% 18% 6% 10% 5% 5% 5% 3 4 5% 19%	2860
November	1st to 10th	Night	20% 19% 7% 11% 5% 5% 4 3 4 5% 16%	2721
	11th to 20th	Night	20% 20% 6% 14% 6% 5% 4 3 4 4 14%	3136
	21st to end	Night	16% 22% 8% 16% 8% 5% 4 3 3 3 12%	3150
December	1st to 10th	Night	7% 20% 9% 18% 11% 9% 5% 3 4 4 10%	5060
	11th to 20th	Night	10% 14% 6% 16% 10% 8% 6% 5% 4 5% 17%	5736
	21st to end	Night	14% 16% 6% 12% 7% 7% 6% 6% 5% 5% 16%	7667

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% 4 9% 9% 4 1	4095
	11th to 20th	Day	75% 4 9% 11% 2	4392
	21st to end	Day	69% 3 5% 17% 6%	5156
February	1st to 10th	Day	59% 7% 10% 17% 7%	1680
	11th to 20th	Day	60% 6% 10% 19% 5%	1795
	21st to end	Day	59% 4 12% 15% 10%	1730
March	1st to 10th	Day	62% 4 5% 14% 12% 3	4580
	11th to 20th	Day	65% 4 7% 14% 9% 1	4854
	21st to end	Day	66% 5% 5% 15% 8%	5949
April	1st to 10th	Day	56% 5% 10% 19% 10% 1	2520
	11th to 20th	Day	54% 4 8% 22% 11% 1	2691
	21st to end	Day	54% 4 8% 19% 13% 1	2742
May	1st to 10th	Day	58% 3 8% 17% 12% 1	8250
	11th to 20th	Day	56% 5% 7% 20% 12%	8737
	21st to end	Day	45% 4 10% 23% 15% 2	9717
June	1st to 10th	Day	52% 5% 10% 20% 11% 1	3150
	11th to 20th	Day	47% 6% 10% 23% 11% 1	3158
	21st to end	Day	47% 6% 13% 23% 10% 1	3360
July	1st to 10th	Day	39% 6% 15% 32% 8%	6757
	11th to 20th	Day	44% 7% 19% 25% 5%	6739
	21st to end	Day	40% 8% 20% 26% 5%	6870
August	1st to 10th	Day	46% 6% 15% 25% 7%	4548
	11th to 20th	Day	34% 6% 18% 36% 6%	4416
	21st to end	Day	42% 6% 17% 25% 10%	4674
September	1st to 10th	Day	50% 6% 15% 23% 5% 1	2407
	11th to 20th	Day	55% 6% 17% 18% 3	2240
	21st to end	Day	56% 5% 12% 21% 7%	2200
October	1st to 10th	Day	58% 6% 14% 17% 4	3436
	11th to 20th	Day	56% 6% 16% 20% 2	2912
	21st to end	Day	68% 6% 10% 13% 3	3180
November	1st to 10th	Day	71% 6% 10% 11% 3	1796
	11th to 20th	Day	77% 5% 8% 8% 1	1480
	21st to end	Day	83% 3 6% 7% 3	1470
December	1st to 10th	Day	76% 5% 7% 9% 2	2350
	11th to 20th	Day	65% 5% 13% 14% 4	2691
	21st to end	Day	74% 3 7% 14% 2	3553
January	1st to 10th	Night	73% 4 10% 8% 4 2	8831
	11th to 20th	Night	78% 4 8% 8% 2	8581
	21st to end	Night	66% 4 7% 16% 6%	9058
February	1st to 10th	Night	63% 5% 9% 17% 6%	2940
	11th to 20th	Night	62% 6% 10% 17% 5%	2721
	21st to end	Night	57% 6% 11% 19% 8%	2076
March	1st to 10th	Night	55% 5% 8% 17% 14% 1	5493
	11th to 20th	Night	64% 4 9% 15% 8%	5325
	21st to end	Night	60% 6% 5% 19% 9%	5267
April	1st to 10th	Night	57% 5% 6% 19% 13%	2100
	11th to 20th	Night	52% 4 9% 21% 12% 1	1878
	21st to end	Night	49% 4 7% 22% 16% 2	1874
May	1st to 10th	Night	52% 4 7% 22% 14% 1	4695
	11th to 20th	Night	53% 5% 9% 19% 13%	4158
	21st to end	Night	46% 4 8% 22% 16% 4	4493
June	1st to 10th	Night	51% 6% 10% 20% 13% 1	1470
	11th to 20th	Night	43% 7% 11% 25% 14% 1	1450
	21st to end	Night	44% 6% 12% 28% 10%	1260
July	1st to 10th	Night	41% 6% 14% 34% 5%	3081
	11th to 20th	Night	43% 8% 20% 23% 7%	3118
	21st to end	Night	38% 6% 18% 34% 3	3688
August	1st to 10th	Night	41% 6% 17% 28% 7%	2588
	11th to 20th	Night	31% 6% 17% 37% 8%	2705
	21st to end	Night	36% 6% 18% 26% 13%	3223
September	1st to 10th	Night	44% 5% 19% 26% 7%	1990
	11th to 20th	Night	49% 7% 20% 21% 3	2140
	21st to end	Night	48% 6% 16% 21% 9%	2200
October	1st to 10th	Night	54% 6% 15% 19% 6%	3742
	11th to 20th	Night	59% 5% 15% 18% 3	4227
	21st to end	Night	67% 6% 11% 13% 3	4610
November	1st to 10th	Night	70% 5% 11% 10% 3	2721
	11th to 20th	Night	74% 5% 10% 10% 2	3136
	21st to end	Night	78% 4 8% 9% 2	3150
December	1st to 10th	Night	79% 4 8% 8% 2	5060
	11th to 20th	Night	69% 4 9% 14% 4	5735
	21st to end	Night	69% 4 9% 16% 2	7667

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	11% 17% 36% 26% 10%	220
	11th to 20th	Day	11% 12% 33% 28% 14% 3	272
	21st to end	Day	13% 10% 30% 31% 13% 3	363
February	1st to 10th	Day	15% 11% 32% 33% 8% 1	330
	11th to 20th	Day	11% 14% 40% 24% 9% 2	330
	21st to end	Day	13% 16% 40% 22% 7% 1	273
March	1st to 10th	Day	14% 15% 38% 23% 9% 2	330
	11th to 20th	Day	12% 15% 41% 24% 6% 2	434
	21st to end	Day	13% 12% 34% 30% 9% 3	594
April	1st to 10th	Day	13% 15% 36% 24% 10% 2	540
	11th to 20th	Day	27% 12% 27% 21% 10% 2	532
	21st to end	Day	21% 11% 29% 27% 9% 3	552
May	1st to 10th	Day	22% 14% 30% 24% 7% 2	753
	11th to 20th	Day	25% 15% 30% 20% 8% 2	775
	21st to end	Day	26% 11% 30% 25% 7% 1	844
June	1st to 10th	Day	25% 12% 32% 23% 7% 2	780
	11th to 20th	Day	19% 11% 28% 29% 10% 2	780
	21st to end	Day	19% 9% 30% 26% 13% 4	780
July	1st to 10th	Day	14% 11% 30% 28% 16% 1	722
	11th to 20th	Day	18% 10% 29% 30% 11% 2	718
	21st to end	Day	15% 8% 28% 27% 17% 5%	794
August	1st to 10th	Day	19% 9% 27% 26% 14% 4	726
	11th to 20th	Day	16% 10% 25% 26% 17% 6%	645
	21st to end	Day	21% 8% 28% 27% 11% 5%	583
September	1st to 10th	Day	22% 10% 30% 27% 10% 2	530
	11th to 20th	Day	25% 12% 29% 23% 9% 2	530
	21st to end	Day	27% 10% 27% 22% 12% 2	530
October	1st to 10th	Day	26% 15% 32% 20% 6% 1	479
	11th to 20th	Day	24% 19% 36% 15% 6% 1	330
	21st to end	Day	29% 16% 29% 20% 5%	363
November	1st to 10th	Day	27% 22% 33% 15% 3	300
	11th to 20th	Day	26% 14% 34% 21% 4 1	220
	21st to end	Day	27% 17% 33% 17% 5% 1	220
December	1st to 10th	Day	18% 15% 27% 26% 12% 1	220
	11th to 20th	Day	17% 15% 36% 22% 10%	220
	21st to end	Day	18% 11% 29% 31% 8% 4	242
January	1st to 10th	Night	16% 10% 34% 31% 8% 1	1050
	11th to 20th	Night	18% 9% 31% 30% 11% 2	1050
	21st to end	Night	14% 6% 32% 32% 13% 3	1155
February	1st to 10th	Night	10% 10% 32% 35% 13% 1	1050
	11th to 20th	Night	11% 8% 33% 34% 12% 2	934
	21st to end	Night	10% 8% 30% 34% 16% 2	692
March	1st to 10th	Night	13% 8% 33% 34% 11% 2	840
	11th to 20th	Night	15% 10% 40% 27% 8% 1	840
	21st to end	Night	17% 9% 34% 27% 13% 2	784
April	1st to 10th	Night	20% 9% 34% 27% 10% 1	630
	11th to 20th	Night	22% 9% 29% 27% 11% 2	623
	21st to end	Night	19% 9% 29% 29% 13% 1	630
May	1st to 10th	Night	21% 10% 32% 28% 7% 1	630
	11th to 20th	Night	24% 11% 31% 26% 8%	446
	21st to end	Night	24% 9% 33% 28% 5%	455
June	1st to 10th	Night	25% 11% 29% 24% 10%	420
	11th to 20th	Night	17% 7% 35% 28% 12%	420
	21st to end	Night	16% 8% 30% 34% 11% 1	420
July	1st to 10th	Night	19% 6% 29% 32% 14%	390
	11th to 20th	Night	12% 6% 33% 41% 8% 1	388
	21st to end	Night	17% 3 25% 37% 16% 2	587
August	1st to 10th	Night	18% 6% 22% 39% 13% 2	597
	11th to 20th	Night	15% 6% 26% 32% 19% 2	594
	21st to end	Night	19% 6% 25% 35% 12% 1	660
September	1st to 10th	Night	20% 6% 27% 35% 11% 1	600
	11th to 20th	Night	25% 8% 32% 26% 9%	740
	21st to end	Night	25% 10% 26% 31% 9% 1	800
October	1st to 10th	Night	30% 11% 31% 22% 6% 1	800
	11th to 20th	Night	30% 10% 27% 22% 9% 2	800
	21st to end	Night	26% 10% 28% 25% 10% 1	880
November	1st to 10th	Night	30% 12% 30% 21% 6%	820
	11th to 20th	Night	31% 12% 26% 23% 8%	1036
	21st to end	Night	26% 13% 31% 22% 7% 1	1050
December	1st to 10th	Night	16% 10% 37% 26% 10% 1	1050
	11th to 20th	Night	16% 11% 34% 25% 11% 3	1050
	21st to end	Night	22% 9% 28% 26% 10% 5%	1155

Page generated at 2026-06-28 02:10:46. Version ac07

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