Oakdale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oakdale clear sky chart from 2005-11-06 to 2024-11-08.

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% 10% 4 8% 5% 5% 5% 4 6% 7% 33%	101407
	Night	15% 11% 4 8% 5% 4 4 3 5% 6% 34%	97658
Transparency	Day	48% 6% 13% 21% 11% 1	105049
	Night	48% 5% 12% 21% 12% 1	102155
Seeing	Day	18% 10% 28% 25% 14% 6%	15181
	Night	19% 9% 28% 30% 12% 1	24566

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	17% 20% 8% 14% 5% 4 4 4 5% 4 15%	2527
	11th to 20th	Day	14% 20% 8% 16% 7% 8% 7% 2 3 4 11%	2728
	21st to end	Day	27% 19% 8% 11% 5% 3 3 3 3 4 13%	3124
February	1st to 10th	Day	16% 15% 5% 12% 7% 6% 5% 3 4 6% 20%	1710
	11th to 20th	Day	14% 13% 6% 13% 7% 5% 4 4 6% 5% 24%	1715
	21st to end	Day	17% 14% 4 11% 7% 5% 4 3 4 5% 25%	1570
March	1st to 10th	Day	19% 14% 5% 10% 5% 4 4 2 4 5% 27%	3299
	11th to 20th	Day	13% 13% 5% 10% 5% 5% 4 3 5% 5% 31%	3480
	21st to end	Day	18% 12% 4 8% 5% 5% 4 3 5% 5% 31%	3815
April	1st to 10th	Day	15% 13% 3 7% 5% 5% 5% 4 5% 7% 31%	2150
	11th to 20th	Day	19% 11% 3 6% 4 4 4 4 5% 7% 33%	2442
	21st to end	Day	19% 10% 3 7% 5% 4 5% 4 5% 7% 32%	2470
May	1st to 10th	Day	18% 7% 3 7% 4 4 4 4 6% 8% 36%	4082
	11th to 20th	Day	17% 8% 2 7% 5% 5% 5% 4 6% 8% 32%	4081
	21st to end	Day	11% 5% 2 6% 4 4 4 4 5% 8% 46%	4657
June	1st to 10th	Day	10% 7% 3 7% 5% 5% 4 5% 6% 9% 40%	2709
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 8% 42%	2850
	21st to end	Day	12% 6% 2 6% 4 4 5% 5% 8% 9% 40%	2850
July	1st to 10th	Day	11% 5% 2 7% 5% 5% 5% 4 6% 9% 40%	4577
	11th to 20th	Day	9% 5% 1 5% 5% 5% 5% 5% 7% 11% 44%	4317
	21st to end	Day	8% 5% 2 6% 5% 6% 5% 5% 7% 10% 40%	4466
August	1st to 10th	Day	13% 6% 2 5% 5% 5% 6% 4 7% 9% 38%	4104
	11th to 20th	Day	9% 6% 2 7% 4 6% 6% 6% 8% 10% 36%	4044
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 5% 6% 9% 42%	4532
September	1st to 10th	Day	11% 6% 2 6% 4 5% 6% 5% 6% 9% 41%	2166
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 9% 45%	2090
	21st to end	Day	17% 8% 2 7% 4 4 5% 4 6% 8% 36%	2090
October	1st to 10th	Day	13% 7% 3 7% 4 4 5% 4 6% 7% 40%	1976
	11th to 20th	Day	19% 9% 3 7% 5% 6% 4 3 5% 7% 32%	1900
	21st to end	Day	21% 10% 3 8% 5% 5% 4 3 5% 7% 28%	2014
November	1st to 10th	Day	13% 10% 4 9% 6% 4 5% 4 5% 7% 34%	1735
	11th to 20th	Day	15% 13% 5% 8% 4 4 4 5% 6% 7% 30%	1640
	21st to end	Day	20% 13% 5% 9% 7% 4 5% 4 5% 6% 23%	1520
December	1st to 10th	Day	16% 15% 5% 12% 6% 5% 4 4 5% 7% 21%	1520
	11th to 20th	Day	18% 16% 6% 10% 6% 5% 4 3 5% 6% 21%	1910
	21st to end	Day	28% 20% 6% 11% 5% 4 4 2 4 4 11%	2547
January	1st to 10th	Night	17% 16% 6% 11% 5% 5% 4 3 4 6% 22%	4428
	11th to 20th	Night	15% 21% 7% 14% 6% 6% 9% 3 3 3 12%	4217
	21st to end	Night	25% 18% 7% 9% 5% 4 3 3 4 3 18%	4532
February	1st to 10th	Night	16% 16% 5% 11% 7% 5% 5% 3 5% 5% 22%	2470
	11th to 20th	Night	16% 15% 5% 9% 6% 4 5% 3 5% 6% 27%	2350
	21st to end	Night	19% 12% 5% 10% 6% 4 5% 4 4 5% 26%	1884
March	1st to 10th	Night	17% 14% 4 8% 5% 4 4 3 4 6% 32%	3553
	11th to 20th	Night	10% 9% 3 7% 6% 5% 5% 4 5% 8% 38%	3480
	21st to end	Night	16% 10% 4 8% 4 4 4 3 4 5% 38%	3817
April	1st to 10th	Night	17% 11% 3 7% 5% 4 4 4 5% 6% 35%	2044
	11th to 20th	Night	18% 8% 3 6% 5% 4 4 3 5% 8% 37%	1687
	21st to end	Night	16% 11% 3 7% 4 5% 4 3 5% 7% 36%	1710
May	1st to 10th	Night	17% 8% 3 7% 5% 4 4 3 6% 7% 37%	2813
	11th to 20th	Night	12% 9% 3 8% 6% 5% 5% 4 6% 8% 35%	2812
	21st to end	Night	11% 5% 2 4 4 4 5% 3 4 7% 50%	2894
June	1st to 10th	Night	11% 5% 3 5% 4 4 4 3 7% 8% 46%	1465
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 7% 9% 45%	1330
	21st to end	Night	10% 5% 2 5% 4 3 5% 3 5% 9% 48%	1330
July	1st to 10th	Night	8% 4 2 5% 4 3 4 3 6% 10% 51%	2388
	11th to 20th	Night	9% 4 1 5% 3 4 3 4 7% 9% 50%	2646
	21st to end	Night	6% 3 2 5% 4 4 4 5% 8% 10% 48%	3087
August	1st to 10th	Night	11% 6% 3 5% 4 4 4 3 5% 8% 46%	2825
	11th to 20th	Night	9% 7% 2 6% 4 4 4 3 6% 6% 49%	2785
	21st to end	Night	8% 5% 2 7% 4 4 5% 4 6% 7% 49%	3124
September	1st to 10th	Night	9% 7% 2 6% 4 4 4 3 5% 7% 48%	1992
	11th to 20th	Night	8% 5% 2 5% 3 3 3 3 5% 7% 55%	2090
	21st to end	Night	15% 7% 3 8% 5% 4 4 4 4 7% 41%	2090
October	1st to 10th	Night	13% 7% 2 6% 5% 4 3 3 5% 6% 46%	2204
	11th to 20th	Night	20% 9% 3 7% 4 4 3 3 5% 5% 37%	2280
	21st to end	Night	22% 8% 3 7% 6% 4 4 3 5% 6% 31%	2580
November	1st to 10th	Night	14% 8% 2 6% 5% 4 4 4 6% 7% 40%	2504
	11th to 20th	Night	16% 11% 3 8% 5% 5% 4 3 5% 7% 31%	2536
	21st to end	Night	21% 14% 3 8% 4 4 4 3 5% 6% 28%	2660
December	1st to 10th	Night	18% 17% 5% 9% 6% 5% 5% 4 5% 6% 21%	2660
	11th to 20th	Night	16% 16% 5% 10% 6% 4 4 4 5% 6% 25%	3285
	21st to end	Night	26% 22% 6% 11% 4 4 4 3 3 4 13%	5106

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	69% 6% 11% 9% 4	2528
	11th to 20th	Day	76% 6% 7% 8% 3	2728
	21st to end	Day	76% 4 9% 7% 3	3124
February	1st to 10th	Day	65% 5% 10% 14% 6%	1710
	11th to 20th	Day	61% 5% 10% 15% 8% 1	1724
	21st to end	Day	62% 4 11% 15% 6% 1	1570
March	1st to 10th	Day	60% 4 10% 20% 5%	3299
	11th to 20th	Day	53% 5% 15% 19% 7% 1	3480
	21st to end	Day	55% 5% 12% 16% 11% 1	3815
April	1st to 10th	Day	50% 5% 13% 20% 11% 1	2150
	11th to 20th	Day	49% 5% 11% 19% 13% 2	2442
	21st to end	Day	51% 5% 13% 18% 12% 2	2470
May	1st to 10th	Day	45% 6% 11% 23% 12% 3	4120
	11th to 20th	Day	46% 9% 16% 20% 8% 1	4085
	21st to end	Day	35% 6% 12% 19% 20% 8%	4671
June	1st to 10th	Day	40% 6% 13% 27% 13% 2	2709
	11th to 20th	Day	36% 7% 14% 23% 17% 2	2850
	21st to end	Day	37% 7% 13% 25% 16% 1	2850
July	1st to 10th	Day	40% 5% 11% 26% 16% 2	4508
	11th to 20th	Day	32% 6% 14% 32% 15% 1	4242
	21st to end	Day	37% 7% 16% 19% 21% 2	4324
August	1st to 10th	Day	39% 7% 15% 24% 14% 1	4091
	11th to 20th	Day	38% 8% 13% 32% 8% 1	4083
	21st to end	Day	37% 6% 13% 31% 12% 1	4531
September	1st to 10th	Day	39% 7% 15% 25% 14% 1	2166
	11th to 20th	Day	34% 6% 12% 32% 16% 1	2090
	21st to end	Day	45% 6% 13% 24% 11% 1	2090
October	1st to 10th	Day	34% 5% 13% 29% 18% 1	3288
	11th to 20th	Day	44% 3 10% 25% 17% 1	3140
	21st to end	Day	45% 5% 15% 25% 10%	3303
November	1st to 10th	Day	49% 6% 12% 22% 10% 2	1735
	11th to 20th	Day	51% 5% 16% 18% 9% 1	1640
	21st to end	Day	62% 5% 12% 16% 5%	1520
December	1st to 10th	Day	62% 6% 14% 14% 4	1520
	11th to 20th	Day	64% 4 14% 13% 5%	1906
	21st to end	Day	78% 4 10% 6% 2	2547
January	1st to 10th	Night	62% 5% 12% 15% 5% 1	4428
	11th to 20th	Night	69% 11% 8% 8% 3	4217
	21st to end	Night	71% 4 8% 13% 3	4532
February	1st to 10th	Night	63% 6% 10% 15% 6% 1	2470
	11th to 20th	Night	58% 4 10% 17% 10% 1	2352
	21st to end	Night	59% 4 10% 18% 8% 1	1884
March	1st to 10th	Night	54% 4 13% 22% 6%	3553
	11th to 20th	Night	42% 6% 15% 21% 15% 1	3480
	21st to end	Night	48% 4 10% 23% 14% 1	3817
April	1st to 10th	Night	50% 5% 10% 20% 13% 2	2044
	11th to 20th	Night	46% 5% 10% 21% 17% 1	1687
	21st to end	Night	47% 5% 9% 20% 15% 4	1710
May	1st to 10th	Night	46% 5% 11% 19% 15% 5%	2840
	11th to 20th	Night	44% 7% 13% 23% 11% 2	2813
	21st to end	Night	33% 6% 11% 23% 21% 6%	2901
June	1st to 10th	Night	35% 6% 11% 28% 18% 2	1465
	11th to 20th	Night	35% 6% 14% 23% 20% 2	1330
	21st to end	Night	34% 6% 12% 27% 20% 1	1330
July	1st to 10th	Night	29% 5% 12% 30% 17% 6%	2348
	11th to 20th	Night	30% 4 14% 33% 18% 1	2598
	21st to end	Night	29% 7% 17% 22% 22% 2	2988
August	1st to 10th	Night	37% 4 14% 26% 17% 2	2814
	11th to 20th	Night	34% 5% 13% 32% 14% 1	2812
	21st to end	Night	34% 5% 11% 31% 18% 1	3124
September	1st to 10th	Night	35% 6% 13% 27% 17% 2	1992
	11th to 20th	Night	28% 6% 13% 32% 20% 2	2090
	21st to end	Night	43% 5% 11% 27% 13% 1	2090
October	1st to 10th	Night	29% 4 8% 30% 27% 1	3672
	11th to 20th	Night	48% 3 10% 22% 18%	3779
	21st to end	Night	43% 4 13% 27% 13% 1	4241
November	1st to 10th	Night	43% 6% 10% 27% 13% 1	2504
	11th to 20th	Night	52% 5% 12% 21% 9% 1	2536
	21st to end	Night	56% 4 15% 18% 6%	2660
December	1st to 10th	Night	63% 5% 13% 14% 4	2660
	11th to 20th	Night	59% 6% 14% 15% 7%	3288
	21st to end	Night	76% 4 10% 7% 3	5106

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	23% 20% 32% 16% 9% 1	270
	11th to 20th	Day	26% 14% 40% 14% 4 1	270
	21st to end	Day	30% 12% 33% 19% 4 1	297
February	1st to 10th	Day	24% 19% 40% 13% 3 1	270
	11th to 20th	Day	24% 20% 36% 19% 1	270
	21st to end	Day	28% 22% 36% 13% 1	225
March	1st to 10th	Day	26% 16% 34% 19% 5% 1	371
	11th to 20th	Day	21% 14% 33% 25% 6% 1	460
	21st to end	Day	28% 13% 30% 22% 6% 1	506
April	1st to 10th	Day	18% 15% 34% 23% 8%	460
	11th to 20th	Day	28% 14% 25% 19% 9% 5%	452
	21st to end	Day	24% 12% 30% 22% 10% 2	460
May	1st to 10th	Day	22% 10% 27% 26% 11% 3	463
	11th to 20th	Day	19% 7% 28% 26% 13% 6%	487
	21st to end	Day	15% 7% 22% 28% 20% 8%	529
June	1st to 10th	Day	11% 8% 30% 29% 18% 4	539
	11th to 20th	Day	12% 7% 30% 33% 14% 4	680
	21st to end	Day	13% 7% 29% 32% 15% 4	680
July	1st to 10th	Day	9% 4 23% 31% 23% 10%	671
	11th to 20th	Day	11% 5% 25% 29% 20% 9%	597
	21st to end	Day	9% 4 21% 28% 26% 12%	532
August	1st to 10th	Day	10% 4 20% 26% 26% 15%	486
	11th to 20th	Day	12% 5% 15% 32% 22% 15%	479
	21st to end	Day	12% 5% 19% 28% 26% 10%	539
September	1st to 10th	Day	12% 5% 21% 28% 23% 11%	490
	11th to 20th	Day	9% 2 18% 26% 31% 14%	490
	21st to end	Day	17% 12% 21% 25% 17% 8%	490
October	1st to 10th	Day	18% 8% 24% 25% 19% 7%	490
	11th to 20th	Day	20% 13% 29% 26% 10% 3	490
	21st to end	Day	26% 11% 38% 18% 6% 1	463
November	1st to 10th	Day	14% 19% 38% 19% 8% 2	291
	11th to 20th	Day	24% 14% 32% 18% 10% 1	237
	21st to end	Day	24% 18% 38% 15% 4 1	180
December	1st to 10th	Day	25% 14% 36% 16% 9% 1	180
	11th to 20th	Day	27% 20% 35% 17% 2	180
	21st to end	Day	33% 16% 30% 17% 3	207
January	1st to 10th	Night	25% 13% 37% 18% 6% 1	950
	11th to 20th	Night	31% 12% 31% 22% 4	818
	21st to end	Night	25% 9% 31% 28% 7%	836
February	1st to 10th	Night	24% 13% 34% 24% 4	760
	11th to 20th	Night	24% 14% 30% 26% 6%	743
	21st to end	Night	26% 13% 38% 21% 3	628
March	1st to 10th	Night	21% 11% 35% 28% 6%	760
	11th to 20th	Night	18% 12% 39% 24% 7% 1	760
	21st to end	Night	22% 11% 30% 28% 8%	836
April	1st to 10th	Night	21% 14% 32% 28% 4 1	745
	11th to 20th	Night	23% 8% 33% 25% 10% 1	563
	21st to end	Night	22% 7% 34% 30% 7%	570
May	1st to 10th	Night	18% 7% 29% 33% 12% 1	570
	11th to 20th	Night	16% 5% 27% 37% 14% 1	561
	21st to end	Night	12% 3 23% 43% 18% 1	509
June	1st to 10th	Night	13% 2 29% 42% 14%	380
	11th to 20th	Night	10% 4 22% 49% 14% 1	380
	21st to end	Night	11% 6% 25% 42% 16% 1	380
July	1st to 10th	Night	7% 2 17% 44% 28% 3	465
	11th to 20th	Night	9% 2 19% 41% 26% 4	552
	21st to end	Night	9% 2 15% 46% 26% 2	624
August	1st to 10th	Night	7% 2 13% 43% 31% 4	567
	11th to 20th	Night	8% 1 15% 39% 32% 5%	564
	21st to end	Night	11% 2 16% 38% 30% 3	627
September	1st to 10th	Night	11% 4 19% 35% 26% 5%	741
	11th to 20th	Night	10% 4 17% 35% 29% 5%	760
	21st to end	Night	16% 7% 18% 37% 18% 5%	760
October	1st to 10th	Night	14% 7% 25% 33% 18% 3	760
	11th to 20th	Night	24% 8% 28% 28% 11% 2	760
	21st to end	Night	25% 11% 29% 29% 5%	836
November	1st to 10th	Night	19% 11% 27% 29% 13% 1	771
	11th to 20th	Night	21% 13% 34% 23% 7% 1	760
	21st to end	Night	28% 12% 30% 23% 8%	760
December	1st to 10th	Night	28% 12% 34% 19% 7%	760
	11th to 20th	Night	23% 15% 36% 23% 4	760
	21st to end	Night	32% 12% 31% 23% 3	990

Page generated at 2024-11-05 08:15:54. Version ac07

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