Ogden
Clear Sky Chart
History

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

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	8% 8% 2 5% 4 3 3 3 5% 6% 51%	105312
	Night	9% 9% 3 6% 4 3 4 3 5% 6% 48%	102459
Transparency	Day	31% 6% 10% 18% 20% 14%	105076
	Night	35% 6% 11% 18% 18% 12%	102284
Seeing	Day	10% 8% 24% 35% 20% 3	15150
	Night	13% 4 20% 40% 21% 2	25159

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	13% 20% 5% 9% 4 4 4 3 4 5% 29%	2858
	11th to 20th	Day	12% 23% 6% 10% 5% 5% 4 3 4 4 25%	2860
	21st to end	Day	12% 19% 6% 9% 5% 4 3 4 9% 8% 22%	3146
February	1st to 10th	Day	15% 16% 4 8% 4 4 4 4 5% 6% 30%	1710
	11th to 20th	Day	13% 16% 4 7% 6% 4 4 4 5% 6% 31%	1726
	21st to end	Day	10% 17% 6% 10% 6% 4 3 3 5% 6% 29%	1570
March	1st to 10th	Day	8% 19% 6% 10% 4 4 4 3 4 6% 32%	3341
	11th to 20th	Day	7% 10% 2 5% 5% 4 4 4 5% 6% 48%	3490
	21st to end	Day	15% 18% 5% 10% 5% 5% 4 4 5% 6% 23%	3825
April	1st to 10th	Day	15% 10% 2 6% 5% 4 4 5% 6% 6% 38%	2109
	11th to 20th	Day	11% 11% 2 7% 4 4 5% 3 5% 7% 41%	2418
	21st to end	Day	10% 9% 3 6% 4 4 4 3 6% 7% 44%	2470
May	1st to 10th	Day	9% 11% 2 7% 5% 4 5% 5% 6% 7% 39%	4110
	11th to 20th	Day	8% 4 1 4 3 3 4 3 6% 9% 56%	4071
	21st to end	Day	9% 5% 2 5% 3 3 4 4 6% 7% 53%	4477
June	1st to 10th	Day	5% 4 1 5% 4 3 3 4 6% 8% 56%	2608
	11th to 20th	Day	6% 4 2 4 3 3 3 3 5% 8% 59%	2673
	21st to end	Day	3 2 1 3 2 2 2 2 4 5% 72%	2748
July	1st to 10th	Day	2 1 1 2 2 2 2 2 3 5% 78%	4275
	11th to 20th	Day	2 3 1 3 2 3 3 3 5% 7% 69%	4110
	21st to end	Day	3 2 1 2 2 2 3 3 5% 6% 70%	4454
August	1st to 10th	Day	4 3 1 4 3 3 3 3 4 5% 68%	4092
	11th to 20th	Day	3 2 1 4 3 3 4 3 5% 6% 67%	4028
	21st to end	Day	3 2 1 2 2 2 2 3 5% 6% 73%	4504
September	1st to 10th	Day	3 2 1 3 2 2 3 3 3 5% 72%	2144
	11th to 20th	Day	4 3 1 4 3 3 3 3 4 5% 66%	2090
	21st to end	Day	6% 3 1 3 2 2 2 2 4 5% 68%	2090
October	1st to 10th	Day	7% 3 1 3 3 3 3 3 3 5% 66%	3335
	11th to 20th	Day	8% 5% 2 4 3 3 3 3 5% 6% 58%	3150
	21st to end	Day	7% 7% 2 6% 3 3 3 3 4 6% 57%	3383
November	1st to 10th	Day	12% 10% 2 6% 4 3 3 4 5% 6% 43%	1719
	11th to 20th	Day	16% 8% 2 5% 3 3 4 2 5% 9% 44%	1710
	21st to end	Day	11% 12% 3 6% 4 4 3 3 6% 6% 43%	1545
December	1st to 10th	Day	12% 14% 3 8% 5% 4 4 3 5% 5% 36%	1520
	11th to 20th	Day	16% 14% 4 9% 5% 4 4 4 5% 8% 28%	1926
	21st to end	Day	10% 14% 5% 8% 5% 5% 5% 4 6% 7% 32%	3027
January	1st to 10th	Night	11% 18% 5% 9% 5% 3 3 3 4 6% 32%	4097
	11th to 20th	Night	17% 18% 6% 9% 5% 4 4 3 4 5% 26%	4110
	21st to end	Night	14% 19% 4 8% 4 4 4 4 8% 7% 25%	4521
February	1st to 10th	Night	14% 15% 3 7% 5% 5% 4 4 5% 6% 33%	2470
	11th to 20th	Night	12% 13% 3 8% 4 4 3 3 5% 6% 40%	2336
	21st to end	Night	9% 16% 4 9% 6% 4 4 4 5% 5% 35%	1884
March	1st to 10th	Night	16% 13% 4 8% 5% 5% 4 3 5% 5% 31%	3532
	11th to 20th	Night	6% 9% 2 6% 4 4 4 4 5% 7% 49%	3490
	21st to end	Night	12% 17% 4 8% 5% 4 5% 3 4 5% 33%	3828
April	1st to 10th	Night	13% 11% 3 6% 4 3 4 3 4 4 45%	2071
	11th to 20th	Night	10% 10% 3 6% 6% 4 3 3 5% 5% 45%	1705
	21st to end	Night	11% 8% 2 6% 4 4 3 3 5% 6% 48%	1710
May	1st to 10th	Night	12% 11% 3 6% 5% 5% 3 4 6% 6% 40%	2860
	11th to 20th	Night	8% 4 2 4 3 3 3 3 5% 7% 60%	2834
	21st to end	Night	11% 5% 2 6% 4 3 4 3 5% 6% 50%	3110
June	1st to 10th	Night	6% 4 2 5% 4 3 4 4 7% 8% 55%	1563
	11th to 20th	Night	7% 3 1 4 3 2 3 3 4 7% 63%	1495
	21st to end	Night	3 2 1 4 2 2 3 2 4 6% 70%	1423
July	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 74%	2668
	11th to 20th	Night	2 3 2 5% 3 4 4 4 6% 9% 58%	2860
	21st to end	Night	3 4 2 4 3 3 4 4 6% 6% 61%	3109
August	1st to 10th	Night	3 3 1 4 4 4 4 4 5% 8% 60%	2847
	11th to 20th	Night	2 4 1 5% 4 4 4 3 5% 6% 60%	2811
	21st to end	Night	2 2 1 3 2 3 3 3 4 5% 71%	3163
September	1st to 10th	Night	4 3 1 3 3 3 3 3 4 5% 68%	2033
	11th to 20th	Night	6% 3 1 3 3 3 3 3 4 5% 65%	2090
	21st to end	Night	6% 3 1 3 2 1 2 2 3 4 70%	2090
October	1st to 10th	Night	6% 3 1 3 2 2 3 2 3 4 70%	3639
	11th to 20th	Night	10% 6% 1 4 3 3 3 3 4 6% 58%	3778
	21st to end	Night	8% 6% 2 5% 3 3 4 3 5% 7% 55%	4170
November	1st to 10th	Night	12% 8% 2 4 4 3 3 3 5% 6% 49%	2482
	11th to 20th	Night	12% 7% 2 7% 3 3 3 3 5% 7% 47%	2470
	21st to end	Night	10% 10% 2 5% 5% 4 4 3 4 6% 46%	2612
December	1st to 10th	Night	13% 12% 4 8% 4 3 3 3 5% 6% 39%	2660
	11th to 20th	Night	16% 13% 3 8% 5% 4 4 4 5% 7% 32%	3271
	21st to end	Night	12% 13% 4 9% 6% 4 4 3 5% 7% 34%	4667

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	56% 11% 17% 13% 4	2859
	11th to 20th	Day	60% 10% 16% 10% 3 1	2860
	21st to end	Day	55% 13% 19% 8% 4 1	3146
February	1st to 10th	Day	55% 9% 15% 14% 7% 1	1710
	11th to 20th	Day	50% 8% 15% 16% 9% 1	1735
	21st to end	Day	53% 8% 14% 16% 8% 1	1570
March	1st to 10th	Day	48% 11% 10% 21% 10% 1	3341
	11th to 20th	Day	33% 8% 13% 34% 12% 1	3490
	21st to end	Day	55% 12% 11% 16% 5% 1	3825
April	1st to 10th	Day	43% 8% 13% 19% 13% 4	2109
	11th to 20th	Day	41% 8% 10% 21% 18% 2	2421
	21st to end	Day	37% 6% 10% 25% 20% 1	2470
May	1st to 10th	Day	37% 7% 11% 21% 18% 5%	4110
	11th to 20th	Day	22% 6% 9% 31% 26% 7%	4074
	21st to end	Day	27% 7% 9% 26% 28% 3	4477
June	1st to 10th	Day	24% 5% 10% 24% 30% 7%	2608
	11th to 20th	Day	23% 5% 7% 17% 28% 20%	2673
	21st to end	Day	15% 2 4 11% 30% 37%	2748
July	1st to 10th	Day	10% 2 4 9% 14% 61%	4210
	11th to 20th	Day	13% 3 5% 9% 25% 45%	4041
	21st to end	Day	14% 4 6% 9% 30% 37%	4314
August	1st to 10th	Day	17% 4 6% 13% 30% 31%	4078
	11th to 20th	Day	16% 4 5% 13% 35% 27%	4067
	21st to end	Day	12% 3 5% 15% 33% 32%	4503
September	1st to 10th	Day	16% 4 6% 15% 30% 30%	2144
	11th to 20th	Day	19% 5% 7% 18% 32% 19%	2090
	21st to end	Day	18% 4 8% 20% 37% 12%	2090
October	1st to 10th	Day	21% 4 6% 15% 33% 21%	3335
	11th to 20th	Day	26% 5% 8% 29% 25% 7%	3150
	21st to end	Day	28% 5% 11% 34% 19% 2	3383
November	1st to 10th	Day	40% 8% 15% 21% 16% 1	1719
	11th to 20th	Day	38% 6% 18% 25% 12%	1710
	21st to end	Day	41% 7% 18% 21% 12% 1	1545
December	1st to 10th	Day	48% 11% 16% 15% 8% 1	1520
	11th to 20th	Day	55% 7% 20% 14% 4	1924
	21st to end	Day	48% 11% 16% 14% 10% 1	3027
January	1st to 10th	Night	52% 11% 17% 15% 5% 1	4097
	11th to 20th	Night	58% 11% 16% 11% 4 1	4110
	21st to end	Night	54% 13% 20% 9% 3 1	4521
February	1st to 10th	Night	51% 8% 16% 19% 6%	2470
	11th to 20th	Night	45% 6% 13% 22% 13% 1	2337
	21st to end	Night	48% 7% 12% 22% 9% 1	1884
March	1st to 10th	Night	48% 8% 12% 19% 12% 1	3532
	11th to 20th	Night	32% 7% 12% 33% 14% 1	3490
	21st to end	Night	49% 9% 11% 24% 7% 1	3828
April	1st to 10th	Night	42% 4 13% 21% 13% 6%	2071
	11th to 20th	Night	39% 7% 9% 24% 20% 2	1705
	21st to end	Night	36% 6% 11% 24% 21% 3	1710
May	1st to 10th	Night	40% 7% 11% 18% 20% 4	2860
	11th to 20th	Night	22% 6% 9% 29% 26% 7%	2835
	21st to end	Night	32% 6% 10% 21% 30% 1	3110
June	1st to 10th	Night	25% 6% 11% 21% 30% 7%	1563
	11th to 20th	Night	21% 4 8% 18% 28% 20%	1495
	21st to end	Night	16% 2 6% 12% 26% 39%	1423
July	1st to 10th	Night	13% 2 5% 7% 14% 59%	2624
	11th to 20th	Night	20% 4 5% 8% 24% 38%	2806
	21st to end	Night	20% 5% 7% 9% 25% 35%	3011
August	1st to 10th	Night	21% 4 6% 11% 27% 31%	2838
	11th to 20th	Night	23% 5% 6% 11% 25% 30%	2838
	21st to end	Night	15% 3 6% 10% 24% 42%	3163
September	1st to 10th	Night	19% 3 7% 12% 25% 34%	2033
	11th to 20th	Night	21% 4 6% 15% 31% 24%	2090
	21st to end	Night	19% 3 6% 17% 35% 21%	2090
October	1st to 10th	Night	18% 4 5% 13% 35% 25%	3639
	11th to 20th	Night	28% 3 5% 27% 28% 9%	3778
	21st to end	Night	29% 4 8% 34% 22% 3	4170
November	1st to 10th	Night	36% 5% 11% 25% 19% 4	2482
	11th to 20th	Night	37% 4 14% 28% 15% 1	2470
	21st to end	Night	40% 5% 14% 26% 13% 2	2612
December	1st to 10th	Night	46% 6% 17% 20% 9% 2	2660
	11th to 20th	Night	50% 9% 19% 16% 6%	3272
	21st to end	Night	50% 8% 17% 14% 10% 1	4667

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	19% 11% 25% 29% 13% 4	270
	11th to 20th	Day	20% 9% 19% 33% 16% 2	270
	21st to end	Day	20% 6% 26% 33% 14% 3	297
February	1st to 10th	Day	22% 10% 29% 26% 10% 1	270
	11th to 20th	Day	17% 11% 34% 27% 10% 1	331
	21st to end	Day	13% 12% 37% 29% 8% 1	382
March	1st to 10th	Day	17% 12% 32% 30% 9% 1	460
	11th to 20th	Day	11% 10% 30% 33% 15%	460
	21st to end	Day	19% 13% 32% 27% 8%	506
April	1st to 10th	Day	15% 14% 27% 28% 15% 1	460
	11th to 20th	Day	14% 18% 30% 27% 10% 1	452
	21st to end	Day	14% 12% 30% 24% 18% 2	460
May	1st to 10th	Day	10% 15% 32% 29% 14% 1	463
	11th to 20th	Day	10% 10% 25% 31% 20% 4	488
	21st to end	Day	9% 10% 22% 33% 23% 4	529
June	1st to 10th	Day	5% 6% 22% 38% 26% 4	628
	11th to 20th	Day	7% 8% 23% 39% 21% 2	680
	21st to end	Day	4 5% 24% 42% 22% 4	578
July	1st to 10th	Day	1 3 20% 46% 28% 2	486
	11th to 20th	Day	3 3 16% 48% 27% 4	484
	21st to end	Day	4 2 10% 49% 31% 4	531
August	1st to 10th	Day	4 4 17% 46% 25% 5%	487
	11th to 20th	Day	3 4 17% 41% 31% 5%	477
	21st to end	Day	5% 3 16% 39% 32% 5%	539
September	1st to 10th	Day	4 4 17% 32% 35% 7%	490
	11th to 20th	Day	6% 5% 24% 33% 27% 6%	490
	21st to end	Day	7% 5% 20% 31% 33% 4	490
October	1st to 10th	Day	11% 6% 22% 28% 28% 6%	400
	11th to 20th	Day	8% 8% 25% 28% 24% 7%	300
	21st to end	Day	8% 12% 22% 38% 20% 1	330
November	1st to 10th	Day	20% 7% 23% 29% 15% 6%	285
	11th to 20th	Day	13% 9% 17% 40% 16% 4	270
	21st to end	Day	15% 7% 20% 30% 22% 6%	270
December	1st to 10th	Day	16% 8% 21% 36% 13% 6%	270
	11th to 20th	Day	19% 7% 25% 39% 10% 1	270
	21st to end	Day	22% 9% 22% 33% 11% 2	297
January	1st to 10th	Night	20% 4 19% 36% 19% 2	760
	11th to 20th	Night	21% 4 18% 39% 16% 3	760
	21st to end	Night	21% 4 18% 38% 14% 3	836
February	1st to 10th	Night	21% 4 24% 38% 12% 1	760
	11th to 20th	Night	17% 4 26% 39% 14% 1	744
	21st to end	Night	15% 7% 28% 37% 12% 1	628
March	1st to 10th	Night	19% 7% 22% 40% 11% 2	760
	11th to 20th	Night	13% 4 23% 43% 16% 1	760
	21st to end	Night	20% 6% 23% 39% 12% 1	836
April	1st to 10th	Night	18% 7% 23% 39% 13% 1	741
	11th to 20th	Night	12% 9% 30% 34% 15%	563
	21st to end	Night	13% 6% 22% 38% 21% 1	570
May	1st to 10th	Night	12% 6% 26% 38% 18% 1	570
	11th to 20th	Night	11% 4 21% 34% 28% 2	561
	21st to end	Night	13% 5% 17% 36% 27% 2	617
June	1st to 10th	Night	6% 6% 18% 39% 29% 1	570
	11th to 20th	Night	8% 6% 21% 42% 23%	545
	21st to end	Night	3 2 21% 41% 30% 3	380
July	1st to 10th	Night	4 1 15% 45% 32% 2	442
	11th to 20th	Night	5% 1 14% 49% 30% 1	552
	21st to end	Night	4 9% 46% 39% 1	624
August	1st to 10th	Night	5% 1 11% 49% 32% 1	567
	11th to 20th	Night	3 1 15% 45% 35% 1	564
	21st to end	Night	5% 3 14% 39% 37% 2	627
September	1st to 10th	Night	5% 3 15% 40% 35% 2	703
	11th to 20th	Night	7% 3 15% 41% 30% 4	760
	21st to end	Night	8% 3 18% 35% 30% 7%	760
October	1st to 10th	Night	10% 4 17% 43% 25% 1	760
	11th to 20th	Night	13% 3 16% 38% 28% 2	760
	21st to end	Night	10% 3 23% 38% 23% 2	836
November	1st to 10th	Night	15% 4 18% 41% 20% 2	764
	11th to 20th	Night	14% 4 20% 44% 16% 3	760
	21st to end	Night	14% 4 22% 37% 20% 3	902
December	1st to 10th	Night	18% 4 23% 39% 14% 1	950
	11th to 20th	Night	22% 5% 20% 39% 13% 1	950
	21st to end	Night	26% 6% 22% 36% 9% 1	917

Page generated at 2024-11-03 11:19:04. Version ac07

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