Evermore Farms
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Evermore Farms clear sky chart from 2005-11-06 to 2026-09-29.

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 5% 5% 4 6% 9% 41%	148703
	Night	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	142698
Transparency	Day	39% 6% 13% 20% 17% 6%	152453
	Night	38% 5% 12% 18% 19% 7%	147020
Seeing	Day	16% 9% 23% 25% 19% 8%	17594
	Night	15% 9% 22% 31% 20% 3	27574

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	15% 6% 2 6% 4 4 4 3 5% 6% 45%	5258
	11th to 20th	Day	11% 6% 2 4 2 2 3 2 4 6% 58%	5280
	21st to end	Day	20% 8% 3 7% 4 4 3 2 4 6% 39%	5840
February	1st to 10th	Day	16% 7% 2 6% 5% 3 4 4 5% 7% 41%	2100
	11th to 20th	Day	21% 7% 2 5% 3 3 3 3 5% 4 44%	2048
	21st to end	Day	17% 8% 2 5% 4 4 4 3 5% 6% 42%	1730
March	1st to 10th	Day	20% 8% 3 6% 4 4 4 3 5% 6% 38%	4897
	11th to 20th	Day	8% 4 2 5% 4 4 4 3 5% 7% 54%	5090
	21st to end	Day	15% 7% 3 7% 4 4 4 3 4 4 46%	5586
April	1st to 10th	Day	11% 5% 2 6% 4 3 5% 3 5% 6% 49%	2310
	11th to 20th	Day	10% 5% 2 6% 3 4 4 3 6% 7% 50%	2438
	21st to end	Day	8% 5% 2 5% 4 3 4 4 6% 8% 51%	2730
May	1st to 10th	Day	14% 7% 2 7% 4 5% 5% 4 6% 8% 39%	7616
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 4 7% 8% 36%	7626
	21st to end	Day	13% 7% 3 8% 5% 5% 6% 4 6% 8% 34%	8391
June	1st to 10th	Day	9% 6% 3 8% 6% 6% 7% 5% 8% 10% 33%	2730
	11th to 20th	Day	5% 5% 2 5% 5% 5% 6% 5% 7% 12% 43%	2730
	21st to end	Day	5% 4 2 6% 5% 6% 7% 6% 9% 12% 37%	2730
July	1st to 10th	Day	7% 5% 2 7% 6% 6% 7% 5% 9% 13% 33%	7680
	11th to 20th	Day	5% 4 2 7% 6% 6% 6% 6% 10% 13% 35%	7680
	21st to end	Day	6% 6% 3 8% 6% 7% 7% 6% 11% 14% 27%	8340
August	1st to 10th	Day	12% 6% 2 7% 6% 6% 7% 6% 9% 14% 25%	6014
	11th to 20th	Day	5% 3 1 5% 4 5% 6% 5% 7% 12% 48%	5790
	21st to end	Day	7% 5% 2 6% 5% 4 6% 4 7% 10% 44%	5920
September	1st to 10th	Day	8% 6% 2 7% 4 5% 6% 4 7% 10% 41%	2310
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 6% 8% 41%	2310
	21st to end	Day	14% 6% 2 6% 4 3 4 3 5% 7% 45%	2288
October	1st to 10th	Day	13% 5% 2 5% 3 4 4 3 5% 7% 51%	2200
	11th to 20th	Day	12% 5% 1 3 3 2 3 3 4 6% 58%	2030
	21st to end	Day	11% 4 2 5% 3 4 4 2 4 5% 56%	2200
November	1st to 10th	Day	12% 5% 2 5% 3 3 3 4 5% 4 54%	1983
	11th to 20th	Day	13% 5% 1 4 3 3 3 2 4 7% 55%	1890
	21st to end	Day	13% 6% 2 4 4 4 3 3 6% 7% 48%	1890
December	1st to 10th	Day	14% 6% 2 6% 4 4 3 3 4 6% 47%	3020
	11th to 20th	Day	16% 7% 2 5% 4 3 3 3 5% 6% 47%	3463
	21st to end	Day	21% 7% 2 5% 3 3 3 3 4 6% 44%	4565
January	1st to 10th	Night	12% 6% 3 6% 4 4 4 3 5% 6% 48%	7635
	11th to 20th	Night	12% 6% 2 5% 3 3 4 4 5% 6% 50%	7680
	21st to end	Night	19% 9% 2 7% 4 3 3 3 4 5% 40%	8325
February	1st to 10th	Night	15% 6% 2 6% 3 4 4 3 5% 5% 46%	2520
	11th to 20th	Night	18% 8% 2 5% 4 4 4 3 4 6% 43%	2458
	21st to end	Night	15% 7% 2 6% 4 4 4 3 4 7% 45%	2076
March	1st to 10th	Night	19% 8% 3 6% 4 3 4 4 5% 7% 38%	5175
	11th to 20th	Night	9% 4 1 4 3 3 5% 3 6% 8% 54%	5090
	21st to end	Night	15% 5% 2 5% 4 4 4 4 5% 6% 47%	5588
April	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 6% 7% 48%	2310
	11th to 20th	Night	11% 5% 2 4 3 3 3 3 5% 8% 54%	2143
	21st to end	Night	7% 4 2 5% 5% 3 4 4 6% 7% 53%	1890
May	1st to 10th	Night	12% 6% 2 7% 4 5% 5% 5% 6% 9% 39%	5237
	11th to 20th	Night	15% 5% 2 6% 5% 5% 5% 5% 7% 9% 38%	5234
	21st to end	Night	13% 8% 3 7% 5% 4 5% 4 6% 9% 37%	5761
June	1st to 10th	Night	9% 7% 3 6% 5% 5% 7% 5% 8% 11% 36%	1890
	11th to 20th	Night	5% 5% 2 7% 5% 5% 5% 5% 8% 12% 42%	1890
	21st to end	Night	6% 4 1 6% 4 5% 6% 6% 9% 12% 39%	1890
July	1st to 10th	Night	8% 6% 2 8% 5% 6% 7% 5% 9% 13% 30%	5278
	11th to 20th	Night	6% 5% 2 8% 6% 7% 7% 6% 10% 14% 30%	5277
	21st to end	Night	7% 7% 3 8% 6% 6% 7% 5% 9% 13% 28%	5736
August	1st to 10th	Night	12% 7% 3 9% 5% 7% 7% 6% 9% 13% 22%	4135
	11th to 20th	Night	5% 3 2 6% 5% 4 6% 5% 8% 14% 43%	4251
	21st to end	Night	8% 6% 2 7% 5% 5% 5% 4 7% 9% 42%	5158
September	1st to 10th	Night	9% 5% 2 6% 5% 5% 6% 4 7% 9% 40%	2310
	11th to 20th	Night	11% 6% 2 6% 5% 5% 5% 4 5% 7% 44%	2310
	21st to end	Night	12% 6% 2 6% 3 5% 4 3 5% 7% 46%	2289
October	1st to 10th	Night	12% 5% 2 5% 3 3 4 3 5% 6% 50%	2200
	11th to 20th	Night	12% 4 1 4 3 3 3 2 4 5% 59%	2368
	21st to end	Night	11% 4 1 5% 3 3 4 3 4 5% 57%	2640
November	1st to 10th	Night	11% 6% 2 5% 3 3 3 3 5% 6% 53%	2529
	11th to 20th	Night	14% 5% 2 5% 3 3 2 3 3 5% 55%	2730
	21st to end	Night	13% 4 2 6% 4 4 4 3 5% 6% 50%	2730
December	1st to 10th	Night	14% 6% 2 5% 3 3 3 3 5% 5% 53%	4380
	11th to 20th	Night	16% 5% 2 5% 3 3 3 3 4 7% 48%	4952
	21st to end	Night	20% 7% 2 6% 4 4 4 3 4 5% 42%	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	41% 2 8% 20% 22% 7%	5259
	11th to 20th	Day	30% 2 3 17% 32% 16%	5280
	21st to end	Day	49% 2 4 16% 20% 9%	5840
February	1st to 10th	Day	42% 4 9% 20% 19% 7%	2100
	11th to 20th	Day	43% 3 5% 20% 22% 6%	2058
	21st to end	Day	43% 5% 7% 15% 22% 9%	1730
March	1st to 10th	Day	48% 3 6% 11% 24% 7%	4897
	11th to 20th	Day	30% 4 7% 16% 23% 20%	5090
	21st to end	Day	42% 3 6% 20% 19% 9%	5586
April	1st to 10th	Day	37% 4 10% 21% 21% 8%	2310
	11th to 20th	Day	33% 5% 9% 20% 24% 10%	2438
	21st to end	Day	31% 6% 12% 25% 24% 4	2730
May	1st to 10th	Day	43% 5% 14% 22% 14% 2	7651
	11th to 20th	Day	44% 5% 16% 21% 12% 3	7630
	21st to end	Day	46% 8% 13% 16% 16% 1	8405
June	1st to 10th	Day	42% 10% 15% 19% 13% 2	2730
	11th to 20th	Day	33% 9% 18% 25% 14% 1	2730
	21st to end	Day	35% 11% 19% 20% 12% 3	2730
July	1st to 10th	Day	40% 8% 25% 22% 4 1	7615
	11th to 20th	Day	38% 10% 31% 19% 3 1	7611
	21st to end	Day	44% 9% 22% 19% 6%	8156
August	1st to 10th	Day	47% 8% 22% 20% 2	6001
	11th to 20th	Day	28% 6% 21% 32% 12% 1	5829
	21st to end	Day	35% 6% 15% 27% 15% 3	5920
September	1st to 10th	Day	38% 7% 15% 19% 16% 4	2310
	11th to 20th	Day	39% 7% 11% 20% 20% 2	2310
	21st to end	Day	39% 6% 11% 20% 19% 5%	2288
October	1st to 10th	Day	31% 4 5% 14% 33% 13%	3590
	11th to 20th	Day	17% 3 4 16% 28% 31%	3283
	21st to end	Day	24% 3 4 21% 35% 14%	3538
November	1st to 10th	Day	33% 4 8% 15% 27% 13%	1983
	11th to 20th	Day	31% 3 7% 21% 26% 12%	1890
	21st to end	Day	35% 5% 7% 19% 26% 7%	1890
December	1st to 10th	Day	39% 4 5% 17% 26% 9%	3020
	11th to 20th	Day	40% 3 8% 21% 21% 8%	3460
	21st to end	Day	42% 3 8% 22% 23% 3	4565
January	1st to 10th	Night	38% 2 8% 22% 24% 6%	7636
	11th to 20th	Night	35% 2 5% 19% 28% 11%	7680
	21st to end	Night	48% 2 4 15% 23% 8%	8325
February	1st to 10th	Night	39% 4 8% 19% 22% 9%	2520
	11th to 20th	Night	44% 4 6% 17% 21% 9%	2459
	21st to end	Night	40% 5% 7% 15% 19% 13%	2076
March	1st to 10th	Night	47% 4 8% 14% 18% 10%	5175
	11th to 20th	Night	29% 3 9% 13% 28% 19%	5090
	21st to end	Night	38% 3 7% 19% 20% 13%	5588
April	1st to 10th	Night	34% 5% 10% 20% 22% 9%	2310
	11th to 20th	Night	29% 4 7% 24% 24% 11%	2143
	21st to end	Night	30% 7% 10% 24% 23% 7%	1890
May	1st to 10th	Night	41% 6% 16% 19% 14% 4	5264
	11th to 20th	Night	42% 6% 15% 22% 14% 1	5235
	21st to end	Night	43% 7% 14% 18% 16% 2	5771
June	1st to 10th	Night	39% 11% 17% 18% 14% 2	1890
	11th to 20th	Night	32% 9% 19% 26% 12% 2	1890
	21st to end	Night	32% 12% 20% 20% 12% 4	1890
July	1st to 10th	Night	42% 8% 26% 19% 4 1	5235
	11th to 20th	Night	42% 11% 30% 14% 2 1	5226
	21st to end	Night	45% 10% 23% 15% 6% 1	5606
August	1st to 10th	Night	51% 9% 21% 17% 4	4124
	11th to 20th	Night	31% 6% 26% 26% 10% 1	4278
	21st to end	Night	38% 5% 14% 25% 15% 2	5158
September	1st to 10th	Night	38% 9% 17% 18% 14% 4	2310
	11th to 20th	Night	38% 7% 13% 19% 18% 5%	2310
	21st to end	Night	37% 7% 12% 17% 21% 6%	2289
October	1st to 10th	Night	34% 3 8% 13% 34% 9%	3590
	11th to 20th	Night	18% 2 4 15% 28% 33%	3854
	21st to end	Night	22% 3 5% 19% 33% 19%	4252
November	1st to 10th	Night	32% 4 8% 15% 27% 14%	2529
	11th to 20th	Night	33% 3 6% 17% 27% 14%	2730
	21st to end	Night	36% 5% 8% 17% 25% 10%	2730
December	1st to 10th	Night	34% 4 5% 18% 31% 7%	4380
	11th to 20th	Night	38% 3 12% 17% 22% 8%	4954
	21st to end	Night	45% 3 6% 22% 21% 3	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	24% 22% 39% 13% 3	330
	11th to 20th	Day	24% 25% 31% 14% 6% 1	330
	21st to end	Day	26% 25% 35% 11% 3	363
February	1st to 10th	Day	24% 15% 43% 14% 4	330
	11th to 20th	Day	36% 18% 33% 11% 2	330
	21st to end	Day	30% 17% 38% 11% 3	273
March	1st to 10th	Day	21% 18% 27% 25% 8%	465
	11th to 20th	Day	21% 15% 34% 20% 8% 1	540
	21st to end	Day	20% 15% 36% 21% 8% 1	594
April	1st to 10th	Day	20% 14% 29% 26% 10% 1	540
	11th to 20th	Day	12% 15% 29% 27% 14% 3	532
	21st to end	Day	12% 9% 27% 29% 19% 4	540
May	1st to 10th	Day	14% 12% 29% 27% 13% 6%	543
	11th to 20th	Day	14% 7% 24% 27% 20% 8%	567
	21st to end	Day	15% 5% 17% 29% 24% 10%	617
June	1st to 10th	Day	12% 4 18% 31% 25% 11%	570
	11th to 20th	Day	8% 5% 17% 29% 25% 18%	570
	21st to end	Day	7% 1 15% 30% 29% 17%	570
July	1st to 10th	Day	7% 2 8% 28% 32% 23%	565
	11th to 20th	Day	7% 1 7% 22% 39% 24%	564
	21st to end	Day	6% 1 10% 30% 36% 17%	620
August	1st to 10th	Day	14% 3 14% 23% 30% 16%	566
	11th to 20th	Day	9% 2 8% 26% 35% 20%	559
	21st to end	Day	13% 3 10% 27% 31% 16%	627
September	1st to 10th	Day	10% 3 14% 30% 29% 15%	570
	11th to 20th	Day	15% 2 12% 29% 31% 11%	570
	21st to end	Day	17% 5% 15% 27% 26% 10%	562
October	1st to 10th	Day	17% 5% 22% 29% 19% 8%	530
	11th to 20th	Day	14% 9% 22% 29% 20% 7%	530
	21st to end	Day	16% 9% 26% 25% 20% 4	583
November	1st to 10th	Day	19% 7% 26% 28% 16% 3	461
	11th to 20th	Day	17% 14% 38% 23% 6% 2	330
	21st to end	Day	15% 17% 32% 25% 8% 2	330
December	1st to 10th	Day	28% 17% 34% 15% 5% 1	330
	11th to 20th	Day	25% 16% 32% 19% 8% 1	330
	21st to end	Day	28% 15% 33% 17% 6% 1	363
January	1st to 10th	Night	22% 18% 33% 22% 5%	840
	11th to 20th	Night	21% 16% 30% 26% 7%	840
	21st to end	Night	21% 18% 34% 25% 3	924
February	1st to 10th	Night	20% 14% 30% 31% 6%	840
	11th to 20th	Night	24% 15% 32% 26% 3	823
	21st to end	Night	21% 15% 34% 27% 3	692
March	1st to 10th	Night	17% 14% 30% 33% 6%	840
	11th to 20th	Night	17% 13% 32% 28% 9%	840
	21st to end	Night	16% 14% 33% 27% 10%	924
April	1st to 10th	Night	15% 14% 31% 28% 12%	840
	11th to 20th	Night	14% 12% 27% 31% 15% 1	712
	21st to end	Night	9% 6% 27% 39% 19%	630
May	1st to 10th	Night	9% 8% 27% 38% 17% 2	630
	11th to 20th	Night	12% 3 21% 38% 23% 3	621
	21st to end	Night	12% 2 16% 34% 29% 6%	683
June	1st to 10th	Night	11% 2 12% 41% 30% 4	630
	11th to 20th	Night	7% 2 13% 34% 33% 11%	630
	21st to end	Night	7% 2 9% 37% 39% 7%	630
July	1st to 10th	Night	8% 1 8% 28% 40% 14%	615
	11th to 20th	Night	6% 1 6% 25% 49% 12%	612
	21st to end	Night	6% 2 8% 30% 45% 8%	690
August	1st to 10th	Night	11% 1 7% 33% 38% 10%	627
	11th to 20th	Night	10% 2 8% 26% 45% 10%	624
	21st to end	Night	12% 2 11% 30% 37% 8%	740
September	1st to 10th	Night	10% 2 11% 30% 38% 8%	840
	11th to 20th	Night	13% 3 11% 31% 38% 5%	840
	21st to end	Night	15% 3 16% 30% 32% 5%	833
October	1st to 10th	Night	14% 3 19% 34% 25% 5%	800
	11th to 20th	Night	13% 7% 22% 32% 23% 4	800
	21st to end	Night	13% 8% 23% 33% 21% 2	880
November	1st to 10th	Night	13% 8% 23% 34% 20% 2	820
	11th to 20th	Night	16% 11% 27% 31% 13% 1	840
	21st to end	Night	14% 12% 28% 31% 14% 1	840
December	1st to 10th	Night	20% 14% 27% 29% 9% 1	840
	11th to 20th	Night	20% 12% 28% 29% 10% 1	840
	21st to end	Night	26% 13% 26% 28% 7%	924

Page generated at 2026-09-26 04:18:42. Version ac07

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