Lytton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lytton clear sky chart from 2005-11-06 to 2024-02-05.

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	6% 9% 4 9% 9% 5% 7% 7% 7% 8% 30%	77529
	Night	5% 9% 4 9% 8% 5% 7% 7% 7% 9% 29%	81175
Transparency	Day	50% 14% 14% 14% 7% 1	77239
	Night	53% 14% 13% 13% 6% 1	81045
Seeing	Day	14% 23% 32% 21% 8% 2	14105
	Night	9% 15% 38% 26% 11% 1	22809

By Month

Percentage Cloud Cover NW (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	3 15% 7% 13% 13% 5% 8% 7% 6% 7% 16%	2219
	11th to 20th	Day	5% 13% 5% 11% 8% 6% 8% 6% 6% 7% 26%	2228
	21st to end	Day	8% 15% 5% 11% 11% 5% 7% 6% 8% 8% 14%	2794
February	1st to 10th	Day	2 10% 5% 10% 12% 6% 8% 8% 8% 10% 20%	1581
	11th to 20th	Day	2 10% 4 10% 8% 5% 8% 7% 9% 9% 27%	1575
	21st to end	Day	2 11% 6% 13% 14% 7% 7% 8% 6% 8% 19%	1385
March	1st to 10th	Day	2 8% 7% 12% 13% 6% 8% 7% 8% 8% 20%	1800
	11th to 20th	Day	2 11% 5% 11% 10% 6% 10% 8% 8% 8% 21%	1967
	21st to end	Day	4 13% 6% 12% 13% 7% 7% 7% 7% 9% 15%	2285
April	1st to 10th	Day	4 13% 7% 11% 12% 7% 8% 7% 6% 7% 18%	2160
	11th to 20th	Day	5% 11% 6% 12% 11% 6% 7% 8% 7% 8% 20%	2175
	21st to end	Day	5% 11% 6% 12% 10% 6% 8% 6% 6% 7% 24%	2470
May	1st to 10th	Day	7% 10% 5% 10% 9% 5% 7% 6% 6% 7% 28%	2520
	11th to 20th	Day	5% 8% 4 9% 9% 5% 8% 7% 7% 10% 28%	2477
	21st to end	Day	12% 9% 5% 10% 9% 5% 6% 6% 6% 6% 26%	2753
June	1st to 10th	Day	12% 8% 4 10% 8% 4 7% 6% 7% 8% 27%	2700
	11th to 20th	Day	11% 8% 5% 10% 10% 5% 7% 6% 7% 8% 24%	2709
	21st to end	Day	7% 6% 3 6% 8% 5% 7% 7% 7% 8% 36%	2700
July	1st to 10th	Day	5% 4 3 6% 7% 4 5% 5% 6% 8% 46%	2700
	11th to 20th	Day	4 3 2 5% 6% 4 6% 6% 6% 7% 49%	2700
	21st to end	Day	3 3 2 4 5% 3 5% 5% 5% 8% 56%	2769
August	1st to 10th	Day	4 3 2 5% 6% 3 5% 5% 5% 7% 52%	2507
	11th to 20th	Day	4 4 2 4 5% 3 4 5% 6% 8% 53%	2382
	21st to end	Day	5% 6% 3 7% 8% 5% 6% 7% 5% 8% 40%	2484
September	1st to 10th	Day	5% 6% 3 7% 6% 4 5% 5% 5% 7% 48%	2160
	11th to 20th	Day	10% 8% 3 6% 7% 4 6% 5% 5% 7% 39%	2160
	21st to end	Day	9% 8% 3 7% 6% 4 6% 6% 7% 9% 35%	1915
October	1st to 10th	Day	8% 8% 3 9% 8% 4 5% 5% 5% 8% 37%	1800
	11th to 20th	Day	8% 8% 4 8% 9% 6% 7% 6% 6% 9% 30%	1800
	21st to end	Day	7% 10% 4 8% 9% 5% 8% 7% 7% 9% 27%	1796
November	1st to 10th	Day	7% 12% 5% 10% 10% 5% 6% 8% 8% 8% 21%	1488
	11th to 20th	Day	3 9% 5% 10% 9% 6% 8% 8% 8% 10% 24%	1520
	21st to end	Day	3 10% 6% 10% 8% 6% 7% 8% 9% 9% 26%	1520
December	1st to 10th	Day	4 11% 4 10% 11% 7% 8% 8% 7% 9% 22%	1405
	11th to 20th	Day	4 12% 6% 12% 10% 6% 7% 7% 7% 9% 19%	1483
	21st to end	Day	4 7% 4 13% 13% 6% 8% 10% 8% 8% 19%	2442
January	1st to 10th	Night	4 16% 7% 13% 11% 7% 9% 8% 8% 7% 12%	4726
	11th to 20th	Night	5% 12% 6% 12% 10% 4 6% 6% 9% 8% 21%	4667
	21st to end	Night	8% 14% 6% 13% 11% 7% 7% 7% 6% 7% 13%	4862
February	1st to 10th	Night	4 13% 5% 12% 10% 5% 6% 8% 9% 9% 19%	2469
	11th to 20th	Night	3 9% 4 9% 8% 5% 8% 8% 8% 10% 28%	2272
	21st to end	Night	3 9% 6% 12% 11% 6% 7% 8% 8% 9% 22%	1871
March	1st to 10th	Night	3 11% 6% 10% 8% 5% 8% 6% 7% 9% 27%	2160
	11th to 20th	Night	2 8% 4 10% 9% 6% 8% 8% 8% 11% 27%	1989
	21st to end	Night	3 9% 4 8% 10% 6% 9% 9% 9% 9% 22%	2070
April	1st to 10th	Night	2 9% 4 9% 9% 5% 8% 7% 8% 9% 29%	1800
	11th to 20th	Night	3 8% 3 7% 9% 5% 8% 8% 9% 11% 29%	1732
	21st to end	Night	5% 8% 4 8% 7% 4 6% 6% 8% 10% 34%	1490
May	1st to 10th	Night	5% 7% 3 6% 8% 4 6% 7% 7% 9% 39%	1440
	11th to 20th	Night	5% 5% 2 6% 6% 4 7% 7% 8% 10% 39%	1416
	21st to end	Night	10% 7% 3 6% 7% 3 6% 7% 6% 9% 36%	1518
June	1st to 10th	Night	9% 7% 3 8% 8% 5% 6% 5% 7% 8% 34%	1260
	11th to 20th	Night	7% 6% 5% 5% 6% 4 6% 6% 8% 11% 36%	1172
	21st to end	Night	5% 5% 2 5% 7% 3 5% 5% 7% 8% 47%	1260
July	1st to 10th	Night	4 4 3 4 5% 4 4 5% 5% 9% 53%	1260
	11th to 20th	Night	3 3 2 3 3 3 5% 5% 6% 7% 60%	1260
	21st to end	Night	3 3 1 2 4 3 3 3 6% 8% 63%	1548
August	1st to 10th	Night	2 3 2 3 3 3 4 4 6% 9% 61%	1432
	11th to 20th	Night	2 3 2 3 4 3 4 4 5% 6% 63%	1516
	21st to end	Night	4 3 1 5% 6% 4 7% 6% 6% 9% 48%	1872
September	1st to 10th	Night	5% 4 1 5% 4 2 5% 6% 5% 8% 55%	1800
	11th to 20th	Night	6% 6% 3 6% 5% 3 5% 6% 5% 9% 46%	1800
	21st to end	Night	8% 7% 2 6% 6% 4 5% 5% 7% 9% 41%	2042
October	1st to 10th	Night	7% 7% 3 7% 6% 3 6% 5% 6% 7% 41%	2160
	11th to 20th	Night	5% 8% 3 8% 8% 5% 6% 7% 7% 7% 35%	2160
	21st to end	Night	7% 9% 4 8% 9% 6% 7% 8% 7% 8% 27%	2560
November	1st to 10th	Night	7% 11% 5% 11% 9% 5% 7% 8% 8% 9% 20%	2590
	11th to 20th	Night	4 10% 6% 9% 9% 5% 8% 8% 9% 9% 24%	2660
	21st to end	Night	5% 12% 5% 10% 9% 5% 8% 9% 7% 9% 21%	2660
December	1st to 10th	Night	4 11% 5% 11% 9% 5% 8% 7% 9% 10% 20%	2749
	11th to 20th	Night	6% 15% 6% 14% 10% 6% 7% 8% 7% 8% 12%	3718
	21st to end	Night	6% 11% 6% 12% 11% 7% 9% 8% 7% 7% 15%	5214

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	65% 11% 13% 9% 2	2219
	11th to 20th	Day	59% 11% 12% 10% 3 6%	2249
	21st to end	Day	70% 12% 8% 8% 3	2794
February	1st to 10th	Day	59% 17% 12% 7% 6% 1	1581
	11th to 20th	Day	54% 15% 14% 11% 6%	1584
	21st to end	Day	62% 14% 9% 11% 3 1	1385
March	1st to 10th	Day	57% 16% 14% 8% 5%	1800
	11th to 20th	Day	56% 17% 14% 9% 4	1967
	21st to end	Day	62% 16% 13% 7% 1	2285
April	1st to 10th	Day	63% 14% 13% 8% 2	2160
	11th to 20th	Day	58% 16% 12% 8% 6%	2175
	21st to end	Day	57% 14% 14% 10% 5%	2470
May	1st to 10th	Day	53% 14% 14% 13% 5% 1	2520
	11th to 20th	Day	47% 16% 16% 16% 5%	2480
	21st to end	Day	57% 12% 13% 14% 4	2754
June	1st to 10th	Day	53% 13% 12% 12% 5% 3	2700
	11th to 20th	Day	54% 16% 17% 11% 2	2709
	21st to end	Day	41% 15% 17% 18% 7% 1	2700
July	1st to 10th	Day	35% 11% 15% 24% 14% 2	2626
	11th to 20th	Day	29% 13% 19% 25% 13% 2	2619
	21st to end	Day	22% 11% 16% 29% 18% 4	2615
August	1st to 10th	Day	28% 12% 15% 26% 16% 3	2490
	11th to 20th	Day	27% 11% 18% 27% 15% 2	2382
	21st to end	Day	38% 13% 18% 21% 8% 2	2484
September	1st to 10th	Day	36% 12% 14% 24% 10% 4	2160
	11th to 20th	Day	44% 12% 11% 17% 14% 3	2160
	21st to end	Day	47% 13% 16% 14% 8% 3	1915
October	1st to 10th	Day	47% 11% 14% 21% 7%	1800
	11th to 20th	Day	53% 13% 13% 15% 6%	1800
	21st to end	Day	55% 13% 13% 14% 5%	1796
November	1st to 10th	Day	60% 16% 11% 10% 3 1	1488
	11th to 20th	Day	57% 15% 13% 9% 5% 1	1520
	21st to end	Day	56% 16% 10% 11% 6% 2	1520
December	1st to 10th	Day	60% 14% 11% 10% 4	1405
	11th to 20th	Day	64% 13% 13% 6% 3	1485
	21st to end	Day	65% 16% 9% 7% 2	2442
January	1st to 10th	Night	70% 12% 9% 6% 3	4726
	11th to 20th	Night	60% 7% 12% 11% 5% 5%	4708
	21st to end	Night	74% 11% 7% 5% 3	4862
February	1st to 10th	Night	64% 11% 10% 10% 5% 1	2469
	11th to 20th	Night	55% 14% 14% 9% 7% 1	2274
	21st to end	Night	60% 13% 11% 11% 5% 1	1871
March	1st to 10th	Night	54% 16% 13% 11% 5%	2160
	11th to 20th	Night	52% 16% 15% 14% 4	1990
	21st to end	Night	54% 20% 16% 9% 2	2070
April	1st to 10th	Night	50% 18% 16% 12% 3	1800
	11th to 20th	Night	47% 21% 14% 11% 6% 1	1732
	21st to end	Night	47% 14% 19% 14% 5%	1490
May	1st to 10th	Night	43% 17% 17% 18% 5% 1	1440
	11th to 20th	Night	40% 17% 21% 17% 5%	1416
	21st to end	Night	46% 14% 17% 19% 4	1518
June	1st to 10th	Night	48% 15% 15% 13% 7% 2	1260
	11th to 20th	Night	41% 20% 20% 13% 6%	1172
	21st to end	Night	34% 17% 21% 19% 8% 2	1260
July	1st to 10th	Night	31% 13% 15% 25% 14% 3	1225
	11th to 20th	Night	22% 14% 20% 29% 13% 1	1218
	21st to end	Night	17% 11% 19% 30% 20% 4	1462
August	1st to 10th	Night	20% 13% 19% 27% 19% 3	1424
	11th to 20th	Night	21% 13% 23% 24% 16% 3	1516
	21st to end	Night	32% 14% 21% 23% 8% 2	1872
September	1st to 10th	Night	28% 15% 18% 26% 11% 2	1800
	11th to 20th	Night	37% 13% 14% 17% 15% 4	1800
	21st to end	Night	45% 14% 15% 15% 9% 2	2042
October	1st to 10th	Night	46% 13% 12% 21% 7% 1	2160
	11th to 20th	Night	51% 13% 13% 16% 7% 1	2160
	21st to end	Night	57% 11% 11% 15% 6%	2560
November	1st to 10th	Night	63% 15% 11% 8% 3 1	2590
	11th to 20th	Night	61% 12% 12% 9% 5% 1	2660
	21st to end	Night	62% 14% 9% 9% 6% 1	2660
December	1st to 10th	Night	61% 12% 11% 13% 3	2749
	11th to 20th	Night	71% 13% 9% 6% 2	3715
	21st to end	Night	64% 14% 11% 7% 4 1	5214

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	8% 22% 41% 18% 9% 3	180
	11th to 20th	Day	9% 19% 39% 19% 13% 1	180
	21st to end	Day	9% 24% 40% 19% 8%	198
February	1st to 10th	Day	12% 25% 50% 10% 2	277
	11th to 20th	Day	8% 24% 41% 24% 2 1	335
	21st to end	Day	12% 25% 37% 19% 7% 1	304
March	1st to 10th	Day	14% 31% 30% 18% 7%	420
	11th to 20th	Day	16% 30% 26% 17% 10% 1	420
	21st to end	Day	19% 32% 28% 13% 7% 1	462
April	1st to 10th	Day	21% 26% 29% 17% 6%	420
	11th to 20th	Day	16% 31% 23% 19% 8% 3	412
	21st to end	Day	16% 30% 29% 16% 8% 2	420
May	1st to 10th	Day	14% 23% 33% 21% 8% 1	423
	11th to 20th	Day	13% 17% 34% 24% 10% 2	448
	21st to end	Day	15% 21% 34% 21% 8% 2	515
June	1st to 10th	Day	18% 31% 32% 14% 5% 1	630
	11th to 20th	Day	16% 27% 33% 18% 5%	639
	21st to end	Day	10% 22% 37% 21% 9% 1	630
July	1st to 10th	Day	10% 21% 34% 25% 8% 2	621
	11th to 20th	Day	8% 22% 34% 26% 8% 2	618
	21st to end	Day	5% 16% 34% 30% 11% 3	515
August	1st to 10th	Day	8% 12% 30% 29% 16% 4	447
	11th to 20th	Day	8% 16% 30% 27% 14% 4	437
	21st to end	Day	10% 22% 35% 22% 8% 3	495
September	1st to 10th	Day	14% 24% 31% 21% 8% 2	450
	11th to 20th	Day	16% 24% 26% 24% 9% 1	450
	21st to end	Day	19% 24% 28% 19% 8% 1	450
October	1st to 10th	Day	17% 24% 24% 19% 12% 3	450
	11th to 20th	Day	20% 26% 26% 15% 11% 2	450
	21st to end	Day	20% 22% 32% 19% 6% 2	311
November	1st to 10th	Day	19% 21% 31% 20% 9% 1	180
	11th to 20th	Day	13% 23% 33% 16% 12% 3	180
	21st to end	Day	9% 21% 36% 22% 8% 4	180
December	1st to 10th	Day	14% 13% 27% 27% 16% 3	180
	11th to 20th	Day	13% 14% 42% 20% 7% 4	180
	21st to end	Day	10% 17% 38% 28% 6% 1	198
January	1st to 10th	Night	12% 23% 40% 18% 6% 1	850
	11th to 20th	Night	10% 18% 42% 23% 7%	841
	21st to end	Night	7% 17% 47% 22% 6% 1	836
February	1st to 10th	Night	10% 20% 45% 19% 5% 1	738
	11th to 20th	Night	7% 13% 49% 24% 6%	704
	21st to end	Night	7% 15% 44% 23% 10%	592
March	1st to 10th	Night	8% 19% 40% 22% 11%	720
	11th to 20th	Night	6% 22% 40% 20% 11% 1	720
	21st to end	Night	8% 18% 39% 24% 11% 1	792
April	1st to 10th	Night	9% 14% 34% 33% 9% 1	720
	11th to 20th	Night	8% 15% 41% 26% 9% 1	664
	21st to end	Night	10% 14% 37% 28% 10% 1	410
May	1st to 10th	Night	7% 12% 35% 31% 14% 1	360
	11th to 20th	Night	7% 8% 29% 39% 17%	354
	21st to end	Night	14% 7% 34% 31% 14%	389
June	1st to 10th	Night	11% 11% 42% 27% 9%	360
	11th to 20th	Night	9% 10% 44% 27% 10%	360
	21st to end	Night	6% 7% 39% 32% 14% 1	360
July	1st to 10th	Night	5% 7% 32% 43% 13% 1	350
	11th to 20th	Night	5% 8% 34% 37% 16%	348
	21st to end	Night	4 5% 27% 42% 22% 1	394
August	1st to 10th	Night	5% 5% 20% 42% 27% 1	358
	11th to 20th	Night	5% 4 27% 35% 27% 2	448
	21st to end	Night	6% 9% 31% 37% 17% 1	684
September	1st to 10th	Night	7% 11% 34% 29% 18% 2	720
	11th to 20th	Night	11% 9% 26% 28% 23% 4	720
	21st to end	Night	14% 16% 29% 26% 14% 2	720
October	1st to 10th	Night	12% 15% 29% 28% 15% 2	720
	11th to 20th	Night	12% 17% 35% 25% 10% 1	720
	21st to end	Night	14% 18% 39% 20% 8% 1	792
November	1st to 10th	Night	15% 20% 39% 21% 4	740
	11th to 20th	Night	11% 19% 44% 18% 7% 1	760
	21st to end	Night	12% 18% 43% 18% 7% 2	760
December	1st to 10th	Night	9% 15% 42% 23% 9% 1	849
	11th to 20th	Night	10% 19% 44% 20% 6%	1021
	21st to end	Night	9% 16% 48% 22% 4	935

Page generated at 2024-02-02 02:20:28. Version ac07

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